High brightness light emitting diodes based on the InAs/GaSb superlattice material system have been developed for use in mid-wave and long-wave infrared optoelectronic systems. By employing a multiple active region device configuration, high optical output has been demonstrated from devices in the 3-5μm and 7-12μm spectral bands. Mid-wave infrared optical output in excess of 0.95mW/sr has been observed from 120×120μm2 devices with peak emission at 3.8μm, and nearly 160μW/sr has been measured from devices of the same size operating at 8μm. Larger devices (1×1mm^2) with output as high as 8.5mW/sr and 1.6mW/sr have been demonstrated with mid-wave and long-wave devices, respectively, under quasi-DC bias conditions. The high switching speed inherent to small area light emitting diodes as well as potentially high optical output make these devices appealing candidates to improve upon the current state-of-the-art in infrared projection technology. Simulation of thermal scenes with wide dynamic range and high frame rates is desirable for calibration of infrared detection systems. Suitable projectors eliminate the need for observation of a live scene for detector calibration, thereby reducing costs and increasing safety. Current technology supports apparent temperature generation of up to approximately 800 Kelvin with frame rates of hundreds of frames per second; strong desire exists to break these barriers. Meeting the requirements of the aforementioned application requires development of the InAs/GaSb superlattice material system on multiple levels. Suppressing parasitic recombination channels via band structure engineering, improving carrier transport between active regions and confinement within active regions, reduction of defect-assisted recombination by optimizing device growth, and improving device fabrication and packaging are all routes requiring exploration. This work focuses on the latter two components of the optimization process, with emphasis on molecular beam epitaxial growth of high quality devices. Particular attention was paid to tailoring devices for thermal imaging applications and the design tradeoffs and limitations which impact that technology. Device performance and optimization success were gauged by electronic, optical, morphological, and structural characterization.

No description available.

The use of SiGe/Si heterostructures in the fabrication of electronic devices results in an improvement of the device performances with respect to bulk silicon. Ion implantation has been proposed as one of the possible technologies to produce these structures and, thus, the aim of this work is to develop an ion beam technology to fabricate strained SiGe heterostructures. The formation of extended defects in SiGe alloy layers formed by high dose Ge+ ion implantation followed by Solid Phase Epitaxial Growth (SPEG) has been investigated by transmission electron microscopy. Rutherford backscattering spectroscopy has also been used to determine the chemical composition and the crystalline quality of the synthesised structures. In addition, X-ray diffraction has been used to evaluate the strain level in selected samples. Two different structures have been studied in this project. The first consisted of "all-implanted" layers, where the Ge+ implants were followed in some cases by additional implants of Si+ and/or C+ ions, prior to SPEG, to investigate methods to inhibit defect formation. The second was achieved by capping the ion beam synthesised SiGe alloy layer by the deposition of a thin film of silicon, in order to realise structures compatible with device dimensions. Single crystal device worthy SiGe alloy layers have been achieved by implantation of Ge+ ions at energies ranging from 70 keV to 400 keV, where the only extended defects observed are EOR defects at a depth correspondent to the a/c interface formed during the Ge+ implant. In some cases, "hairpin" dislocations have also been observed in the vicinity of the EOR defects and extending up to the surface. Both types of defects are annihilated after post-amorphisation with 500 keV Si+ and replaced with dislocation loops at a depth of about 1 fj,m. For each Ge+ implantation energy a critical value of the peak germanium concentration exists above which the structures relax through the formation of stacking faults or "hairpin" dislocations nucleated in the vicinity of the peak of the germanium concentration depth profile and extending up to the surface. A critical value of the elastic energy stored in the structures (~300 mJ/m2) has been determined above which ion beam synthesised SiGe alloys relax, independently of the implantation energy. This empirical approach has been found to successfully account for the results obtained in this work as well as in many other studies reported in the literature. "Hairpin" dislocations formed under different experimental conditions have been investigated by plan view TEM and have been found to have the same crystallographic orientation () and Burgers vector (b= a ). Their formation has been explained within a "strain relaxation model". For a regrowth temperature of 700° C, all samples investigated by XRD have been found to be almost fully strained, including samples containing relaxation-induced defects, indicating that, under these conditions, the energy transferred to the defects is very low. C+ co-implantation has been successfully used to reduce both relaxation-induced defects and EOR dislocation loops. It is noted that a mixed technology entailing both layer deposition and ion implantation to produce the Si/SiGe/Si device structures requires extra process steps to control surface contaminations, pre cleaning and/or native oxide formation, resulting in increased fabrication costs. In this work an " all-implanted" route to the synthesis of Si/SiGe/Si device structures is therefore described, which exploits all of the advantages given by ion implantation.

No description available.

Superior properties of Silicon Carbide (SiC), such as wide bandgap, high breakdown field and high thermal conductivity, have made it the frontrunner to replace Silicon for applications requiring high breakdown strength, mechanical and radiation hardness. Commercial SiC devices are already available, although their expected performance has not yet been realized due to a few problems related to device fabrication technologies, such as selective doping. This work explores non-traditional techniques for SiC doping (and selective doping in particular) based on previously unknown types of defect reactions in SiC and novel epitaxial growth techniques, which offer advantages over currently available technologies. Recent developments in SiC epitaxial growth techniques at MSU have enabled the growth of high quality SiC epitaxial layers at record low temperatures of 1,300°C. Lower growth temperatures have enabled highly doped epilayers for device applications. Prototypes of SiC PiN diodes fabricated, demonstrated low values of the series resistance associated with anodes grown by the low temperature epitaxial growth technique. At room temperature, 100 ìm-diameter diodes with a forward voltage of 3.75 V and 3.23V at 1,000 A/cm2 before and after annealing were achieved. The reverse breakdown voltage was more than 680 V on average, even without surface passivation or edge termination. Reduced growth temperatures also enabled the possibility of selective epitaxial growth (SEG) of SiC with traditional masks used in the SEG in Si technology. Previously, SEG of SiC was impossible without high temperature masks. Good quality, defect free, selectively grown 4H-SiC epilayers were obtained using SiO2 mask. Nitrogen doped selectively grown epilayers were also obtained, which were almost completely ohmic, indicating doping exceeding 1x1019 cm-3. Moreover, conductivity modulation via defect reactions in SiC has been reported as a part of this work for the first time. The approach is based on a new phenomenon in SiC, named Recombination Induced Passivation (RIP), which was observed when hydrogenated SiC epilayers were subjected to above bandgap optical excitation. Additional acceptor passivation, and thereby modification of the conductivity of the epilayer, was observed. Results of investigations of the RIP process are presented, and conductivity modulation techniques based on the RIP process are proposed.

Neste trabalho, estudamos o crescimento de camadas semicondutoras de compostos III-V pela técnica de epitaxia por feixe molecular (MBE). Um grande esforço foi inicialmente realizado para entender o funcionamento do sistema inteiro e otimizar o uso de cada instrumento disponível para a caracterização in situ. Demos uma ênfase particular ao estudo da dopagem homogênea de camadas do tipo p usando duas novas técnicas e, pela primeira vez, obtivemos com sucesso camadas do tipo p crescidas pela co-evaporação de átomos de Si sobre susbtratos de GaAs (001). Finalmente, camadas de alta mobilidade eletrônica foram conseguidas, assim como espelhos de Bragg (DBRs) de alta refletividade. Estes dois tipos de estrutura possuem numerosas aplicações na indústria de microeletrônica e optoeletrônica / In this work, we studied the growth o f III-V semiconductor compounds by molecular beam cpitaxy (MBE). Much efTort was initially spem to understand the functioning of the whole system and optimize the use o f some specific instruments available for m si tu characterization. We gave some emphasis to the homogeneous doping o f p-type layers using two new techniques and, for the fírst time, a thick p-type GaAs layer was successfully grown using co-evaporation o f Si atoms on top o f (00 I) GaAs substrates. Finally, layers with high electron mobility were obtained, as well as distributed Bragg reflectors (DBRs) showing high retlectivity. These two types of structures have many applications in microelectronics and optoelectronics industry.

Neste trabalho, estudamos o crescimento de camadas semicondutoras de compostos III-V pela técnica de epitaxia por feixe molecular (MBE). Um grande esforço foi inicialmente realizado para entender o funcionamento do sistema inteiro e otimizar o uso de cada instrumento disponível para a caracterização in situ. Demos uma ênfase particular ao estudo da dopagem homogênea de camadas do tipo p usando duas novas técnicas e, pela primeira vez, obtivemos com sucesso camadas do tipo p crescidas pela co-evaporação de átomos de Si sobre susbtratos de GaAs (001). Finalmente, camadas de alta mobilidade eletrônica foram conseguidas, assim como espelhos de Bragg (DBRs) de alta refletividade. Estes dois tipos de estrutura possuem numerosas aplicações na indústria de microeletrônica e optoeletrônica / In this work, we studied the growth o f III-V semiconductor compounds by molecular beam cpitaxy (MBE). Much efTort was initially spem to understand the functioning of the whole system and optimize the use o f some specific instruments available for m si tu characterization. We gave some emphasis to the homogeneous doping o f p-type layers using two new techniques and, for the fírst time, a thick p-type GaAs layer was successfully grown using co-evaporation o f Si atoms on top o f (00 I) GaAs substrates. Finally, layers with high electron mobility were obtained, as well as distributed Bragg reflectors (DBRs) showing high retlectivity. These two types of structures have many applications in microelectronics and optoelectronics industry.

The present study aims at clarifying the effects of processing parameters and substrate orientation on the epitaxial growth of Ni on polycrystalline Cu by electrodeposition from a sulfamate solution. The deposits were analyzed by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), auger electron spectroscopy (AES) and transmission electron microscopy (TEM). Two morphologies: rough and smooth, of the substrate surface were introduced by electropolishing. Auger electron spectroscopy showed that Ni was deposited on both areas without preference. However, the deposition rate for the rough area was slightly higher at a low current density of 0.01 A/dm2. At higher current densities, both areas possessed the same rate of deposition. In-plane TEM results demonstrated that Ni deposited on Cu epitaxially regardless the orientation of the Cu grains, electrolyte temperature and current density. EBSD analysis indicated that the Ni epilayer with an orientation of <001>//ND grew epitaxially to as thick as 12 £gm, whereas randomly oriented Ni nucleated on the epilayer having orientations of <011>//ND or <-111>//ND on prolonging deposition at current of 10 A/dm2. In other words, the epitaxial growth of Ni on Cu cannot be sustained to a thickness of hundreds of micrometers without a <001>//ND orientation.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第14050号 / 工博第2962号 / 新制||工||1439(附属図書館) / 26329 / UT51-2008-F442 / 京都大学大学院工学研究科電子物性工学専攻 / (主査)教授 鈴木 実, 教授 髙岡 義寛, 教授 藤田 静雄 / 学位規則第4条第1項該当

Kyoto University (京都大学) / 0048 / 新制・論文博士 / 博士(工学) / 乙第12695号 / 論工博第4084号 / 新制||工||1555(附属図書館) / 29947 / (主査）教授 平尾 一之, 教授 田中 勝久, 教授 三浦 清貴 / 学位規則第4条第2項該当