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"Due to the high variation of critical device parameters inherent in integrated circuit manufacturing, modern integrated circuit designs have evolved to rely on the ratios of similar devices for their performance rather than on the absolute characteristics of any individual device. Today's high performance analog integrated circuits depend on the ability to make identical or matched devices. Circuits are designed using a tolerance based on the overall matching characteristics of their particular manufacturing process. Circuit designers also follow a general rule of thumb that larger devices offer better matching characteristics. This results in circuits that are over designed and circuit layouts that are generally larger than necessary. In this project we develop a model to predict the mismatch in a pair of NPN bipolar transistors. Precise prediction of device mismatch will result in more efficient circuit deigns, smaller circuit layouts and higher test yields, all of which lead to into more reliable and less expensive products."

Using GaAs HBT provided by AWSC to construct Gummel Poon static model.then using the GaAs HBT processing of GCS to design MMIC power amplifier for the 1.9~2.0 GHz PCS system. This power amplifier exhibits an output power of 27dBm and a power added efficiency as high as 32% at an operation voltage of 3.4V.

The fabrication processes development for on III-nitride (III-N) heterojunction bipolar transistors (HBTs), heterojunction field-effect transistors (HFETs) and metal-insulator-semiconductor field-effect transistors (MISFETs) were performed. D.c, microwave and quasi-static I-V and C-V measurements were carried out to characterize the fabricated III-N transistors and diodes. The GaN/InGaN direct-growth HBTs (DG-HBTs) grown on free-standing GaN (FS-GaN) substrates demonstrated a high current gain (hfe) > 110, high current density (JC) > 141 kA/cm2, and high power density (Pdc) > 3 MW/cm2. The first III-N DG-HBT showing fT > 8 GHz and fmax > 1.3 GHz were also demonstrated on sapphire substrates. Recessed-gate AlGaN/AlN/GaN HFETs demonstrated Vth = 0 V with 0.17 V deviation across the sample. Baliga's figure of merit is 240 MW/cm2 was achieved. Current collapse was eliminated and the dynamic on-resistance was reduced by 67% after using a remote-oxygen-plasma treatment. Normally-off recessed-gate AlGaN/AlN/GaN MISFETs with Vth = 0.9 V were also fabricated with the remote-oxygen-plasma treatment. Low leakage current (< 1 pA/mm), high on-off ratio (> 2.2E11) are achieved. These achievements suggest that high-performance III-N transistors are very promising for high-power switching and microwave amplification. Findings concerning remaining process issues and implications for future research are also discussed.

Dissertation (Ph.D.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Ces travaux de thèse traitent de la modélisation d’un interrupteur bipolaire commandable monolithique bidirectionnel en tension et en courant et s’inscrivent dans la gestion de l’énergie dans l’habitat. L’objectif est de concevoir un interrupteur à faible perte énergétique capable de s’intégrer au sein d’une électronique de commande intelligente.Ces travaux s’intéressent dans un premier temps aux différentes solutions existantes destinées à notre application. A travers cette étude, on présente ainsi les avantages et les inconvénients des interrupteurs discrets ou encore des solutions monolithiques. On s’intéresse ensuite à l’étude d’un transistor bipolaire de puissance symétrique vertical. A l’aide de simulations par éléments finis, une étude bidimensionnelle et statique a permis de valider sa fonctionnalité à savoir son aptitude à fonctionner sous le réseau alternatif domestique. L’étude se concentrera ensuite sur les différentes technologies destinées à l’améliorer. En optant pour des caissons fortement dopés judicieusement placés au niveau de la base, il est démontré que les performances d’un tel composant peuvent être augmentées grâce au phénomène d’autoblindage. Finalement, dans le but de simplifier la réalisation de cet interrupteur, la technologie du RESURF sur SOI a été retenue. La structure, latérale, a ensuite été étudiée grâce à des simulations statiques bidimensionnelles puis tridimensionnelles qui ont mis en valeur l’intérêt de cette technologie tant au niveau de la conception qu’au niveau de la réalisation de la structure. / This study deals with the modeling of a monolithic switch bidirectional in current and voltage with full turn-off control for household appliances. The goal is to design a low losses switch which can be integrated to smart electronics functions. These works are focused, first, on discrete and monolithic existing solutions designed for such appliances before pointing out their main advantages and drawbacks. Monolithic structures are preferred over discrete ones thanks to their easiness to be integrated among other structures on the same substrate. The study is focused then on a vertical and symmetrical power bipolar transistor. 2D static simulations in finite elements performed on the structure confirm its ability to work on the mains. Further studies underline the possibility to improve it. By implementing around the active base heavily doped caissons which create a shielding effect, one can increase the structure performances. Finally, to simplify the switch processing steps, SOI RESURF technology is chosen. The lateral structure is studied thanks to 2D and 3D simulations which emphasize the benefits of such technology on both its design and manufacturing process.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2017-03-21T19:41:42Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO MALANA FINAL.pdf: 2413280 bytes, checksum: 40727bc7ff951331cb16c7c787dd0919 (MD5) / Made available in DSpace on 2017-03-21T19:41:43Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO MALANA FINAL.pdf: 2413280 bytes, checksum: 40727bc7ff951331cb16c7c787dd0919 (MD5) Previous issue date: 2016-07-28 / Capes / Transistores bipolares de junção - TBJ possuem uma característica inerente à sua construção física que é o fator de amplificação do sinal produzido, ou seja, amplificação da corrente. Fótons de megavoltagem, ao interagirem com o material semicondutor são capazes de produzir o que é chamado de fotocorrente, ao mesmo tempo em que provocam danos na estrutura cristalina do transistor. O objetivo desta dissertação foi caracterizar o TBJ do tipo BC846 para feixes de fótons de megavoltagem com a finalidade de entender o comportamento deste dispositivo para que futuramente seja desenvolvido um novo método dosimétrico visando complementar os métodos já existentes. O estudo concerniu em caracterizar um TBJ para se analisar como tal dispositivo eletrônico pode ser utilizado como detector de radiação no modo ativo, isto é, em mensurar em tempo real a dose, taxa de dose, dependência energética, e os efeitos direcional e de tamanho de campo de irradiação. Os experimentos foram realizados utilizando um simulador de placas de água sólida com o transistor posicionado no eixo central do feixe em uma profundidade de 5 cm, tamanho de campo padrão, 10 x 10 cm², e uma distância fonte-superfície de 100 cm. Os resultados mostram que o TBJ pode funcionar como detector em feixes de radioterapia desde que seja obedecido certos critérios técnicos relacionados ao comportamento elétrico do dispositivo antes e durante a irradiação. Uma perda percentual média de ±3% na sensibilidade do dispositivo foi registrada após cada irradiação. Essa variação guarda uma proporcionalidade com a dose absorvida e foi encontrada resposta semelhante mesmo com transistores que possuem diferentes fatores de amplificação da corrente. / Bipolar Junction Transistor - BJT have a characteristic inherent to their physical construction, which is the amplification factor of the produced signal, i.e., current amplification. Megavoltage photons interacting with the semiconductor material are capable of producing what is called photocurrent, while causing damage to the crystalline structure of the transistor. The aim of this work was to characterize the BJT type BC846 for MV photon beams in order to understand the behavior of this mechanism to be developed in the future a new dosimetric method to complement existing methods. The study's concerned characterization of a BJT to be analyzed as such electronic device may be used as a radiation detector in the active mode, i.e., measuring in real time the dose, dose rate, energy dependence, and directional effects and size radiation field. The experiments were performed using a solid water phantom with the transistor positioned at the central axis of the beam at a depth of 5 cm, standard field size, 10 x 10 cm², and a source-surface distance of 100 cm. The results show that the BJT may function as a detector in radiotherapy beam since certain technical criteria are met related to the electrical behavior of the device before and during the irradiation. An average percentage loss of ± 3% in the device sensitivity was recorded after each irradiation. This variation is in proportion to the dose absorbed and one can see similar response even with transistors having different amplification factors of the current.