Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / Vita. / Includes bibliographical references. / Ph.D.

O auto sombreamento das folhas posicionadas nas porções inferiores do dossel de plantas pode limitar a produtividade em cultivos tutorados. Assim, a produtividade do tomateiro pode ser aumentada por meio da suplementação luminosa posicionada no interior do dossel, técnica conhecida como interlighting. O sistema de condução do tomateiro também interfere na distribuição da radiação solar, além de afetar os tratos culturais, a competição intra e entre plantas e a relação entre as partes vegetativas e reprodutivas. Desta forma, o objetivo deste trabalho foi avaliar a influência do sistema de condução de minitomate cultivar \'Sweet Grape\' em diferentes números de hastes por planta (duas, três e quatro hastes) e da suplementação luminosa com módulos de LED na produtividade e qualidade dos frutos, na eficiência do uso de água e nutrientes, além da morfologia das plantas e fatores relacionados ao manejo cultural, em ambiente protegido nas condições climáticas do sudeste brasileiro. Ao longo do ciclo de cultivo foram avaliados os seguintes parâmetros: volume irrigado, pH, condutividade elétrica, porcentagem e volume da solução drenada pelos vasos. As colheitas foram realizadas semanalmente, a partir de 90 dias após o transplante. Os frutos colhidos foram classificados, contados e pesados para a obtenção do número e massa de frutos grandes, médios, pequenos, comercial, não comercial e total. Amostras de frutos e tecidos foliares foram coletadas em cinco períodos e avaliadas quanto ao teor de sólidos solúveis, pH, acidez titulável e concentração de ácido ascórbico nos frutos e teor de nutrientes nas folhas. Além disso, ao final do ciclo cultural, foram realizadas as medições dos seguintes parâmetros morfológicos nas plantas: comprimento de hastes, número de cachos normais e bifurcados por hastes e diâmetro apical, mediano e basal das hastes. A suplementação luminosa apresentou aumento no número e na massa de frutos grandes e médios, elevando a produtividade total em 12%. Plantas com duas e três hastes apresentaram maior acúmulo de massa total de frutos, porém plantas com três hastes apresentaram maior massa de frutos não comerciais, com redução na massa de frutos comerciais. A maior eficiência no uso de água e nutrientes foi alcançada em plantas cultivadas com duas hastes. Plantas com quatro hastes demandaram mais solução nutritiva comparada às plantas com duas e três hastes. Esta maior demanda de solução, acarretou em aumento da condutividade elétrica da solução drenada. Plantas com quatro hastes apresentaram maiores teores de sólidos solúveis nos frutos. A suplementação luminosa também resultou em aumento do teor de sólidos solúveis e ligeiro aumento no teor de ácido ascórbico nos frutos. A suplementação luminosa favoreceu o acúmulo de nitrogênio, fósforo e potássio nas folhas do tomateiro. Desta forma, conclui-se que a suplementação luminosa é uma estratégia de manejo tecnicamente viável nas condições climática estudada. O sistema de condução de haste afeta a produtividade e qualidade dos frutos do tomateiro. Plantas com duas hastes além de apresentar maior produtividade de frutos comerciais, mostrou-se a estratégia mais eficiente no uso da água e nutrientes. / The auto shading of leaves located within lower part of plant canopy can limit productivity of the tutored crops. Therefore, tomato productivity can be enhanced through supplementation of light positioned within the canopy using a technique known as interlighting. In addition, management system also affects the distribution of solar radiation, cultural practices as well as intra and between plants competition, which changes the relationship between vegetative and reproductive parts. The objective of this study was to evaluate the influence of different numbers of stems per plant (two, three and four stems) and light supplementation with LED modules in productivity and quality of the fruit of cherry tomato cv. \"Sweet Grape\". Furthermore, it was quantified the efficient use of water and nutrients, plant morphology and factors related to cultural management. The experiment was conducted in a greenhouse located in Piracicaba, southeastern Brazil, using a randomized block design with four replications. Throughout crop cycle were evaluated the following parameters: Irrigated water volume, pH, electrical conductivity, percentage and volume of drained solution. Fruit samples were collected weekly from 90 days after transplantation of tomato seedlings. The harvested fruits were sorted, counted and weighed to obtain number and weight of large, medium, small, commercial, non-commercial and total fruits. Fruit samples and leaf tissues were collected in five periods for quantifying soluble solids, pH, titratable acidity and concentration of ascorbic acid in fruit and nutrient content in the leaves. Furthermore, in the end of the crop cycle, measurements of the following plant morphological parameters were performed: length stems, number of normal and bisected by stems clusters and apical, middle and basal diameter of the stems. Our findings showed that light supplementation induced higher number and mass of large and medium commercial fruit, increasing total productivity by 12%. Two- and three-stem plants had higher total mass accumulation of fruit, but three-stem plants had greater mass of non-commercial fruit, with a reduction in the mass of commercial fruits. The more efficient use of water and nutrients was achieved by two-stem plants. Four-stem plants demanded more nutrient solution compared to two- and three-stem plants, resulting in an increased electrical conductivity of the drained nutrient solution. Four-stem plants had higher soluble solids in the fruit. The light supplementation also resulted in an increase of soluble solids and a slight increase in the ascorbic acid content in fruits. The light supplementation favored the accumulation of nitrogen, phosphorus and potassium within tomato leaves. We concluded that the light supplementation is a technically feasible management strategy in the climatic conditions studied. The management system affects the productivity and quality of cherry tomato fruits. Two stem plants had higher productivity of commercial fruits, as well as it proved to be the most effective strategy in the use of water and nutrients.

No description available.

Time resolved imaging is concerned with the measurement of photon arrival time. It has a wealth of emerging applications including biomedical uses such as fluorescence lifetime microscopy and positron emission tomography, as well as laser ranging and imaging in three dimensions. The impact of time resolved imaging on human life is significant: it can be used to identify cancerous cells in-vivo, how well new drugs may perform, or to guide a robot around a factory or hospital. Two essential building blocks of a time resolved imaging system are a photon detector capable of sensing single photons, and fast time resolvers that can measure the time of flight of light to picosecond resolution. In order to address these emerging applications, miniaturised, single-chip, integrated arrays of photon detectors and time resolvers must be developed with state of the art performance and low cost. The goal of this research is therefore the design, layout and verification of arrays of low noise Single Photon Avalanche Diodes (SPADs) together with high resolution Time-Digital Converters (TDCs) using an advanced silicon fabrication process. The research reported in this Thesis was carried out as part of the E.U. funded Megaframe FP6 Project. A 32x32 pixel, one million frames per second, time correlated imaging device has been designed, simulated and fabricated using a 130nm CMOS Imaging process from ST Microelectronics. The imager array has been implemented together with required support cells in order to transmit data off chip at high speed as well as providing a means of device control, test and calibration. The fabricated imaging device successfully demonstrates the research objectives. The Thesis presents details of design, simulation and characterisation results of the elements of the Megaframe device which were the author’s own work. Highlights of the results include the smallest and lowest noise SPAD devices yet published for this class of fabrication process and an imaging array capable of recording single photon arrivals every microsecond, with a minimum time resolution of fifty picoseconds and single bit linearity.

This thesis explores Single-Photon Avalanche Diodes (SPADs), which are solid-state devices for photon timing and counting, and concentrates on SPADs integrated in nano-scale CMOS. The thesis focuses on: the search for new theory regarding Geiger-mode operation; proving the utility of calibrated Technology Computer- Aided Design (TCAD) tools for accurately simulating SPADs for the first time; the investigation of how manufacture influences device operation; and the integration of high performance SPADs into CMOS which rival discrete devices. The accepted theories of SPAD operation are revisited and it is discovered that previously neglected minority carriers have many significant roles such as determining: after-pulsing, Dark Count Rate (DCR), bipolar “SPAD latch-up,” nonequilibrium DCR, and “quenching”. The “quenching” process is revisited and it is concluded that it is the “probability time” of ≈100-200ps, and not the previously thought latching current that is important. SPADs are also found to have transient negative differential resistance. The new theories of SPADs are also supported by steady-state 1D, 2D and 3D TCAD simulations as well as novel transient simulations and videos. It is demonstrated as possible to simulate DCR, Photon Detection Efficiency (PDE), guard ring performance, breakdown voltage, breakdown voltage variation, “quenching,” and transient operation of SPADs with great accuracy. The manufacture of SPADs is studied focusing on the operation and optimisation of guard rings and it is found that ion implantation induced asymmetry from the tilt and rotation/twist is critical. Where symmetric, guard rings fail first along the <100> directions due to enhanced mobility. Process integration rules are outlined for obtaining high performance SPADs in CMOS while maintaining compatibility with transistors. The minimisation of tunnelling with lightly-doped junctions and the reduction of ion implantation induced defects by additional annealing are found essential for achieving low DCR. The thesis demonstrates that it is possible to realise high performance SPADs in CMOS through the innovation of a “Deep SPAD” which achieves record PDE of ≈72% at 560nm with >40% PDE from 410-760nm, combined with 18Hz DCR, <60ps FWHM timing resolution, and <4% after-pulsing which is demonstrated to have potential for significant further improvement. The findings suggest that CMOS SPAD-based micro-systems could outperform existing photon timing and counting solutions in the future.

No description available.

Neste trabalho, foram realizados estudos de propriedades elétricas e de eletroluminescência em diodos emissores de luz (OLED) contendo modulação energética de poços de potencial para elétrons e buracos (tipo I), poços esses posicionados na região central da camada ativa. A camada ativa é composta por poços simples e duplos, de espessura de 5 e 10nm, de Poli (fenilenovinileno), PPV (Eg = 2,4 eV), dispostos entre duas barreiras de Polifluoreno ou PFO (Eg = 3,0 eV) de espessura 40 nm. Os filmes de PFO foram obtidos a partir de uma solução em Clorofórmio via spin coating e os de PPV a partir de um precursor solúvel em agua via spin assistant LbL, técnica essa que permitiu o crescimento alternado de filmes de PFO e filmes extremamente finos de PPV mesmo em vista da ortogonalidade de seus solventes. Camadas injetoras de polieletrólitos foram depositadas adjacentes ao catodo para diferenciar injeção eletrônica da injeção de buracos. Foram feitos dispositivos contendo somente uma camada de PFO de 80 nm, chamados referência, para comparação do efeito dos poços nos dispositivos com um e dois poços de potencial. Na caracterização foram utilizadas as técnicas de microscopia confocal, com o intuito de demonstrar o crescimento efetivo das camadas, e medidas elétricas de corrente (IxV) e eletroluminescência (LxV) por voltagem. Medidas do perfil de intensidade ao longo do filmes e espectros de fotoluminescência em três regiões distintas da área total do dispositivo mostraram que as camadas de PPV de aproximadamente 5 e 10 nm estavam homogêneas e que recobriam bem as camadas de PFO. Os espectros de eletroluminescência dos dispositivos mostraram que as diferenças energéticas entre os orbitais &#960; (&Delta;EHOMO= 0,54 eV) e &pi;* (&Delta;ELUMO = 0,37 eV) do PFO e PPV foram suficientes para causar o aprisionamento e recombinação dos portadores dentro do poço, resultando em emissões características do PPV com picos bem definidos próximos a 520 nm, bastante distintas das emissões dos dispositivos referência, contendo somente PFO (banda larga e não definida de emissão com &lambda; > 480 nm). A presença dos poços de potencial alterou significativamente as propriedades dos dispositivos levando a diminuição da voltagem de acendimento (Von) para 3,5 V mesmo para dispositivos contendo camada injetora que dificultava a injeção eletrônica. Quando há apenas um poço de potencial na camada ativa dos dispositivos, com ou sem camada injetora, o regime de corrente para voltagens abaixo de 3,5 V é ôhmico e unipolar, sendo ditado por buracos, mas quando a voltagem é maior do que 3,5 V o regime de corrente fica limitado pelo portador minoritário, o elétron. Surpreendentemente, quando são colocados dois poços na camada ativa, separando os portadores, tanto corrente como a formação excitônica e consequente recombinação, ficam sujeitas a um processo de tunelamento do portador majoritário, o buraco. / In this work, studies of electrical properties and electroluminescence in organic light emitting diodes (OLED) containing energetic modulation of potential wells for charge carriers (type I), positioned in the central region of active layer. The active layer is composed of single and double wells of Poly (phenylenevinylene), PPV (2.4 eV), arranged between two barriers of polyfluorene, PFO (3.0 eV), with 40 nm thickness. The PFO films were obtained from a chloroform solution by spin coating and PPV from a water soluble precursor via spin assistant LbL technique, a technique that has allowed the alternate growth of PFO films and extremely thin PPV films from a orthogonal solvent to chloroform, water. Injection layers of polyelectrolytes were deposited adjacent to the cathode to differentiate electronic injection from hole injection. Confocal microscopy measurements showed that the PPV layer of 5 to 10nm thickness were homogeneous and covered PFO layers entirely. Electroluminescence measurements of the devices showed that the energetic difference between &#960; (&Delta;EHOMO = 0.54 eV) and &pi;* (&Delta;ELUMO = 0.37 eV) orbitals from PFO and PPV were enough to cause the charge carriers efficient trapping and recombination in the well, resulting in PPV characteristic emission peaks near to 520 nm, quite different from the reference device emission containing only PFO (broad emission band in the lower energy range). The current measurements showed that the presence of potential wells in the middle of the active layer is responsible for effective change in electrical properties of devices such as carrier density n, &mu; the mobility and conductivity. When there is only one potential well in the active layer, with or without injection layer, the current regime for voltages below 3.5 V is ohmic and unipolar, being dictated by holes, but when the voltage is greater than 3.5 V current regime is limited by the minority carrier, the electron. Surprisingly, when two wells are placed in the active layer, separating the carriers, both current as the excitonic formation and subsequent recombination are subject to a tunneling process by the majority carrier, the hole.

Neste trabalho foram avaliadas as principais características dosimétricas de diodos crescidos pelos métodos de Fusão Zonal (FZ) e Czochralski magnético (MCz), resistentes a danos de radiação, quando aplicados em dosimetria de processos de irradiação industrial com elétrons (1,5 MeV) e raios gama (60Co). O sistema dosimétrico proposto baseia-se no registro de valores de correntes elétricas geradas nos diodos devido à passagem da radiação ionizante. A uniformidade de resposta de um lote de dispositivos foi analisada para os diodos FZ do tipo n irradiados com raios gama. Para uma dose de até 5 kGy obteve-se um coeficiente de variação de 1,25% dos valores de corrente elétrica registrados. A queda da sensibilidade dos diodos com o acúmulo de dose (Total Ionizing Dose TID) foi observada, de acordo com o esperado, para ambos os diodos FZ e MCz, sendo mais acentuada para dispositivos do tipo n ou com resistividade menor, quando irradiados com raios gama. Nos procedimentos de irradiação com elétrons foram utilizados dois protótipos de sonda dosimétrica, sendo que um deles foi projetado para evitar a deterioração dos contatos elétricos e da metalização dos diodos, fenômeno observado durante o desenvolvimento do projeto. A queda da sensibilidade dos diodos FZ e MCz pré-irradiados foi de aproximadamente 10% e 40%, respectivamente, durante os procedimentos de irradiação com elétrons para uma dose acumulada total de 1,25 MGy. A influência dos danos causados por esse tipo de radiação nas propriedades elétricas dos diodos FZ e MCz foi avaliada por meio das medições de corrente de fuga e da capacitância em função da tensão de polarização. A corrente de fuga, que aumenta com a dose de radiação acumulada, não contribui significativamente para a formação do sinal de corrente durante a irradiação, uma vez que os diodos são operados no modo fotovoltaico, ou seja, sem tensão de polarização. Para o diodo MCz não foram observadas alterações significativas dos valores de tensão de depleção total, evidenciando sua maior tolerância aos danos induzidos pela radiação, como esperado. Como durante os procedimentos de irradiação com elétrons há uma variação acentuada dos valores de temperatura, a influência deste parâmetro para as medições de corrente elétrica foi avaliada por meio da extrapolação dos valores de corrente de fuga até 35°C. A contribuição da corrente de fuga para a corrente induzida pela radiação, devido ao aumento da temperatura, não ultrapassa 0,1% para os diodos FZ e MCz. A influência do tipo de radiação, elétrons ou raios gama, na pré-dose dos diodos foi avaliada para o dispositivo FZ do tipo n e observou-se que a pré-irradiação com elétrons é mais eficiente no tocante à queda da sensibilidade dos dispositivos. Os resultados apresentados neste trabalho indicam a potencialidade da aplicação dos diodos FZ e MCz como dosímetros em processos de irradiação de rotina com raios gama e elétrons. Vale ressaltar que a vantagem do sistema proposto reside na possibilidade de acompanhamento em tempo real dos processos envolvidos, sobretudo para elétrons, permitindo a monitoração dos parâmetros dos aceleradores, tais como velocidade de esteira e corrente elétrica de feixe. / In this work the main dosimetric characteristics of rad-hard Float Zone (FZ) and magnetic Czochralski (MCz) diodes to electrons (1.5 MeV) and gamma (60Co) radiation are evaluated. The dosimetric system proposed is based on electrical current measurements due to radiation interactions on the devices. The batch response uniformity was studied for the n-type FZ diodes irradiated with gamma rays. The coefficient of variation of the current measurement was about 1.25% at 5 kGy of accumulated dose. A sensitivity decrease with the increase of the accumulated dose (Total Ionizing Dose TID) was observed for both FZ and MCz diodes. For gamma irradiation, these effect is more pronounced for n-type or smaller resistivity diodes. Two types of dosimetric probe were used on the electron irradiation procedures, one of them specially designed to avoid the deterioration of the electrical contacts and the diodes metallization. The sensitivity of the preirradiated FZ and MCz diodes fell about 10% and 40%, respectively, during electron irradiation at 1.25 MGy of accumulated dose. The effect of electron radiation damage on the electrical properties of the diodes was studied by the means of leakage current and capacitance measurements as a function of bias voltage. The leakage current increases with the accumulated dose but does not contributes significantly to the current signal, since the diodes are operated in photovoltaic mode, without bias voltage. For the MCz diode no change in the full depletion voltage was observed, which indicates its higher tolerance to radiation-induced damage, as expected. During electron irradiation the temperature increases and in order to determine its influence for the current signals, the leakage current values were extrapolated up to 35 °C. The contribution does not exceed 0.1% for FZ and MCz diodes. The effect of the radiation type, electrons or gamma rays, on the predose procedures was analyzed for the FZ n-type device and was observed that the electron pre-irradiation is more efficient regarding the sensitivity decrease. The present work indicates the potential application of FZ and MCz diodes as dosimeters in gamma rays and in electron routine irradiation processes. It is worth noting that the proposed system advantage relies on the possibility of real-time monitoring of electron accelerator parameters.

Neste trabalho, foram realizados estudos de propriedades elétricas e de eletroluminescência em diodos emissores de luz (OLED) contendo modulação energética de poços de potencial para elétrons e buracos (tipo I), poços esses posicionados na região central da camada ativa. A camada ativa é composta por poços simples e duplos, de espessura de 5 e 10nm, de Poli (fenilenovinileno), PPV (Eg = 2,4 eV), dispostos entre duas barreiras de Polifluoreno ou PFO (Eg = 3,0 eV) de espessura 40 nm. Os filmes de PFO foram obtidos a partir de uma solução em Clorofórmio via spin coating e os de PPV a partir de um precursor solúvel em agua via spin assistant LbL, técnica essa que permitiu o crescimento alternado de filmes de PFO e filmes extremamente finos de PPV mesmo em vista da ortogonalidade de seus solventes. Camadas injetoras de polieletrólitos foram depositadas adjacentes ao catodo para diferenciar injeção eletrônica da injeção de buracos. Foram feitos dispositivos contendo somente uma camada de PFO de 80 nm, chamados referência, para comparação do efeito dos poços nos dispositivos com um e dois poços de potencial. Na caracterização foram utilizadas as técnicas de microscopia confocal, com o intuito de demonstrar o crescimento efetivo das camadas, e medidas elétricas de corrente (IxV) e eletroluminescência (LxV) por voltagem. Medidas do perfil de intensidade ao longo do filmes e espectros de fotoluminescência em três regiões distintas da área total do dispositivo mostraram que as camadas de PPV de aproximadamente 5 e 10 nm estavam homogêneas e que recobriam bem as camadas de PFO. Os espectros de eletroluminescência dos dispositivos mostraram que as diferenças energéticas entre os orbitais &#960; (&Delta;EHOMO= 0,54 eV) e &pi;* (&Delta;ELUMO = 0,37 eV) do PFO e PPV foram suficientes para causar o aprisionamento e recombinação dos portadores dentro do poço, resultando em emissões características do PPV com picos bem definidos próximos a 520 nm, bastante distintas das emissões dos dispositivos referência, contendo somente PFO (banda larga e não definida de emissão com &lambda; > 480 nm). A presença dos poços de potencial alterou significativamente as propriedades dos dispositivos levando a diminuição da voltagem de acendimento (Von) para 3,5 V mesmo para dispositivos contendo camada injetora que dificultava a injeção eletrônica. Quando há apenas um poço de potencial na camada ativa dos dispositivos, com ou sem camada injetora, o regime de corrente para voltagens abaixo de 3,5 V é ôhmico e unipolar, sendo ditado por buracos, mas quando a voltagem é maior do que 3,5 V o regime de corrente fica limitado pelo portador minoritário, o elétron. Surpreendentemente, quando são colocados dois poços na camada ativa, separando os portadores, tanto corrente como a formação excitônica e consequente recombinação, ficam sujeitas a um processo de tunelamento do portador majoritário, o buraco. / In this work, studies of electrical properties and electroluminescence in organic light emitting diodes (OLED) containing energetic modulation of potential wells for charge carriers (type I), positioned in the central region of active layer. The active layer is composed of single and double wells of Poly (phenylenevinylene), PPV (2.4 eV), arranged between two barriers of polyfluorene, PFO (3.0 eV), with 40 nm thickness. The PFO films were obtained from a chloroform solution by spin coating and PPV from a water soluble precursor via spin assistant LbL technique, a technique that has allowed the alternate growth of PFO films and extremely thin PPV films from a orthogonal solvent to chloroform, water. Injection layers of polyelectrolytes were deposited adjacent to the cathode to differentiate electronic injection from hole injection. Confocal microscopy measurements showed that the PPV layer of 5 to 10nm thickness were homogeneous and covered PFO layers entirely. Electroluminescence measurements of the devices showed that the energetic difference between &#960; (&Delta;EHOMO = 0.54 eV) and &pi;* (&Delta;ELUMO = 0.37 eV) orbitals from PFO and PPV were enough to cause the charge carriers efficient trapping and recombination in the well, resulting in PPV characteristic emission peaks near to 520 nm, quite different from the reference device emission containing only PFO (broad emission band in the lower energy range). The current measurements showed that the presence of potential wells in the middle of the active layer is responsible for effective change in electrical properties of devices such as carrier density n, &mu; the mobility and conductivity. When there is only one potential well in the active layer, with or without injection layer, the current regime for voltages below 3.5 V is ohmic and unipolar, being dictated by holes, but when the voltage is greater than 3.5 V current regime is limited by the minority carrier, the electron. Surprisingly, when two wells are placed in the active layer, separating the carriers, both current as the excitonic formation and subsequent recombination are subject to a tunneling process by the majority carrier, the hole.

This thesis reports a novel system capable of testing both the spectral responsivity and the spatial quantum efficiency uniformity of heterostructure photodiodes using optical fiber coupled radiation. Testing was performed to confirm device specifications. This study undertakes to quantify the spectral bandwidth of an AlGaAs I GaAs double heterostructure photodiode and two InGaAs I InP double heterostructure PIN photodiodes at D.C., through the use of spatial scanning. The spatial scanning was done using lasers at 670 nm, 780 nm, 848 nm, 1300 nm, and 1550 nm, coupled through singlemode optical fiber. The AlGaAs I GaAs material system covers the 600 - 870 nm wavelength region of research interest in the visible spectrum. The InGaAs I InP material system covers the 800 - 1650 nm region which contains the fiberoptic communications spectrum. The spatial measurement system incorporates a nearly diffraction limited spot of light that is scanned across the surf ace of nominally circular photodiodes using a piezoelectric driven stage. The devices tested range in size from 17 to 52 μin diameter. The smallest device scanned has a diameter approximately four times the diffraction limit of the radiation used for spatial scanning. This is the smallest diode yet reported as being spatially mapped. This is the first simultaneously reported spectral and spatial scans of the same heterostructure PIN photodiodes in the InGaAs I InP and AlGaAs I GaAs systems. The testing arrangement allows both spectral and spatial scans to be taken on the same stage. The diodes tested were taken from intermediate runs during their process development. All testing was performed at room temperature. This study describes the mechanical assembly, calibration and testing of a spatial quantum efficiency uniformity measurement system. The spectral quantum efficiency was measured with low power, incoherent broadband radiation coupled through multimode fiber from a tunable wavelength source to the device under test. The magnitude was corrected to the measured peak external quantum efficiency (Q.E.), determined during spatial scanning at a mid-spectral bandwidth wavelength using continuous wave (CW) higher power lasers. A procedure to improve the accuracy of the correction is recommended. This process has been automated through the use of National Instruments LabVIEW II software. The results from this procedure are plotted to show 2.5 D (pseudo 3D) and 2 D contour spatial quantum efficiency maps. These results give a quantified map of the relative homogeneity of the response. The non-homogeneity of the spatial scans on the smallest devices has not previously been reported. The Q.E. measurements made agree well with previously published results for similar device structures. The AlGaAs I GaAs device achieved a peak external Q.E. of 58.7% at 849 nm with -lOV bias. An InGaAs I InP device achieved 63.5% at 1300 nm with the same bias. The Q.E. results obtained are compared to theoretical calculations. The calculations were performed using the best optical constant data available in the literature at this time. The measured peak Q.E. was found to agree with the theoretical calculations to within 16% at longer wavelengths for both devices tested.