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ABSTRACT: This paper reviews the reliability problems of compound semiconductor transistors for microwave applications. These devices suffer from specific failure mechanisms, which are related to their limited maturity, with the exception of the GaAs MESFETs, which exhibit a stable technology and an assessed reliability. The metallizations employed in high electron mobility transistors (HEMTs) already benefit from this assessment. However, HEMT are affected by concerns related to hot carriers and impact ionization. The trapping of carriers and the generation of defects in the different layers are responsible for the observed instabilities. The stability of the base dopant is the main reliability concern for heterojunction bipolar transistors (HBTs). Beryllium outdiffuses from the base into the emitter and causes device degradation. Carbon has a lower diffusivity, but is affected by the presence of hydrogen, which prompts gain variations. Finally the hot carriers reliability concern in SiGe HBTs is briefly reviewed.
Microelectronics Reliability. 01/2001;
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ABSTRACT: In this study cathodoluminescence spectroscopy has been used for the first time in order to detect the base dopant outdiffusion induced by current stress in AlGaAs/GaAs Be-doped HBTs. The results provide evidence for base dopant diffusion along the growth direction of the HBT structure and suggest that the REID mechanism may be responsible. Therefore, cathodoluminescence can be used as a nondestructive technique to study beryllium outdiffusion
High Performance Electron Devices for Microwave and Optoelectronic Applications, 1997. EDMO. 1997 Workshop on; 12/1997
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ABSTRACT: The major concern for reliability of Berillium doped HBTs is the diffusion of the base dopant towards the emitter. This degradation can be enhanced by the device self-heating and/or by REID mechanism. In order to separate the thermal and REID components to the Berillium outdiffusion we performed a pulsed current stress on AlGaAs/GaAs HBTs. In this paper we report on results obtained with different values of the duty cycles for this current.
Microelectronics Reliability. 38:1233-1237.
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ABSTRACT: This papers reports on the microcharacterization of devices for optoelectronic and high-speed electronic applications by spectrally resolved cathodoluminescence. The advantages offered by the high lateral resolution, monochromatic imaging and depth resolved spectral analysis of the technique are presented. In particular, Inp based semiconducting optical amplifiers and GaAs based pump lasers for optical fiber communications are characterized from the point of view of compositional inhomogeneities and defect generation in the active regions. GaAs based heterojunction bipolar transistors and high electron mobility transitors are studied to respectively reveal Be outdiffusion from the base and break down walkout after bias aging. GaAs based solar cells are also investigated to show the correlation between dislocations and impurity gettering. Finally the limits of the technique are briefly discussed.
Microelectronics Reliability.
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ABSTRACT: The Heterojunction Bipolar Transistor (HBT) features some characteristics that make it a very promising device in the telecom field. For these applications, the reliability is a key issue. The aim of the present paper is to summarise the most relevant reliability concerns, from whose the HBT suffers, as the stability of the ohmic contact, the presence of defects, and the stability of the base dopant. Since in the last years the Si/SiGe HBT has emerged as a strong competitor against the III-V HBT, a paragraph has been devoted to summarise the reliability concerns of the Si/SiGe HBT.
