The electron, gamma and neutron radiation degradation of III-V semiconductors and heterojunction bipolar transistors (HBTs) is investigated in this thesis. Particular attention is paid to InP and InGaAs materials and InP/InGaAs abrupt single HBTs (SHBTs). Complete process sequences for fabrication of InP/InGaAs HBTs are developed and subsequently employed to produce the devices, which are then electrically characterized and irradiated with the different types of radiation. A comprehensive analytical HBT model is developed and radiation damage calculations are performed to model the observed radiation-induced degradation of SHBTs. The most pronounced radiation effects found in SHBTs include reduction of the common-emitter DC current gain, shift of the collector-emitter (CE) offset voltage and increase of the emitter, base and collector parasitic resistances. Quantitative analysis performed using the developed model demonstrates that increase of the neutral bulk and base-emitter (BE) space charge region (SCR) components of the base current are responsible for the observed current gain degradation. The rise of the neutral bulk recombination is attributed to decrease in a Shockley-Read-Hall (SRH) carrier lifetime, while the SCR current increase is caused by rising SCR SRH recombination and activation of a tunneling-recombination mechanism. On the material level these effects are explained by displacement defects produced in a semiconductor by the incident radiation. The second primary change of the SHBT characteristics, CE offset voltage shift, is induced by degradation of the base-collector (BC) junction. The observed rise of the BC current is brought on by diffusion and recombination currents which increase as more defects are introduced in a semiconductor. Finally, the resistance degradation is attributed to deterioration of low-doped layers of a transistor, and to degradation of the device metal contacts. / Graduation date: 2001

No description available.

No description available.

Transmission Electron Microscope (TEM) studies have been carried out of emitter regions in polysilicon contacted emitter bipolar transistors. The preparation of suitable TEM thin foils is described. In addition a technique is developed for the observation and quant jtative interpretation of the break-up of the interfacial oxide layers observed in these samples. The effect of annealing the samples prior to emitter dopant implantation (pre-annealing) is investigated for phosphorus and arsenic doped samples, implanted into a polysilicon layer 0.4μm thick, with a dose of 1x10¹⁶cm². Two wafer pre-cleans have been used prior to polysilicon deposition to produce a thin oxide (0-8Å) and a thicker oxide (14Å). In the presence of the thinner oxide, the phosphorus doped samples enhance epitaxial regrowth of the polysilicon layer compared with the arsenic doped or undoped samples. In the presence of the thicker oxide, no difference is observed between the samples. A mechanism is proposed to explain this. The mechanisms controlling the gain of a phosphorus doped device are investigated and a model proposed to explain the observed electrical characteristics. It is concluded that there are two mechanisms responsible for the observed supression of hole current. Firstly tunnelling through the interfacial oxide and secondly some blocking effect of the interface. Carrier transport in the polysilicon is not believed to contribute to this supression. A dopant sensitive etch has been applied to TEM thin foils containing fully processed emitters in state-of-the-art devices. The shape of the emitter dopant distribution is revealed in such devices for the first time, and a 2-D profile is obtained from the emitter. It is shown that reduction in the emitter depth to 8OOÅ or less does not alter the emitter dopant geometry. The technique is demonstrated to be capable of resolving spatial separations of dopant iso-concentration contours of 100Å or less.

Techn. Hochsch., Diss.--Zürich, 2006.

Thesis (M.S.)--Ohio University, November, 1993. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, June, 1994. / Title from PDF t.p.

Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Cressler, John D.; Committee Member: Laskar, Joy; Committee Member: Lee, Chin-Hui; Committee Member: Morley, Thomas; Committee Member: Papapolymerou, John

Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Member: John Cressler; Committee Member: John Papapolymerou; Committee Member: Joy Laskar; Committee Member: Thomas Morley; Committee Member: William Hunt.

D.Ing. (Electrical & Electronic Engineering ) / In recent years, bipolar transistors have become available with large current ratings (300A-1DODA). The purpose 01 this study is to analyse the modelling 01 these devices, with a view to applying the results to detailed power electronic circuit design (for example base drive and snubber circuits). In contrast to the many curve-filling approaches existing in this field, a model which correctly represents the physical mechanisms is desirable, in order to characterise the device behaviour with a minimum number of parameters. Existing modelling techniques, which have mostly been developed for low current devices, are examined in detail to determine their validity for high current 8JTs. Alter a survey of the literature, the assumptions contained in the lundamental first order theory are investigated, together with the most important second order ellecls. This is followed by a detailed experimental investigation, to establish the dominant mechanisms for both de and dynamic operation. The behaviour 01 large power devices is dominated by conductivity modulation 01 the lightly doped collector region. This means that the Gummel-Poon model, which is based on ellects in the base is not the most appropriate for high current modelling. II also found that the the simple charge control equation can give accurate results for dynamic modelling. The dynamic saturation region 01 operation is described by a simple model, based on the quantity 01 stored charge. This is an improvement on the currently used Gummel-Poon models. The findings are all incorporated into a new model, which is included in a version of the SPICE network simulation program and then tested experimentally. The importance 01 the reverse conduction mode 01 operation is discussed and some techniques for modelling this region are presented, together with some experimental results. II is shown conclusively that the developed device based approach, models the behaviour of the devices adequately for converter design purposes, over a wide range of operating conditions.