1f:T4be,Failure modes and mechanisms of AlGaN/GaN high-electron-mobility transistors are reviewed. Data from three de-accelerated tests are presented, which demonstrate a close correlation between failure modes and bias point. Maximum degradation was found in "semi-on" conditions, close to the maximum of hot-electron generation which was detected with the aid of electroluminescence (EL) measurements. This suggests a contribution of hot-electron effects to device degradation, at least at moderate drain bias (V _DS <30 V). A procedure for the characterization of hot carrier phenomena based on EL microscopy and spectroscopy is described. At high drain bias (V _DS >30-50 V), new failure mechanisms are triggered, which induce an increase of gate leakage current. The latter is possibly related with the inverse piezoelectric effect leading to defect generation due to strain relaxation, and/or to localized permanent breakdown of the AlGaN barrier layer. Results are compared with literature data throughout the text.20:T454,Threshold voltage fluctuation has been experimentally studied, using a newly developed test structure utilizing an 8 k-NMOSFET array. It has been experimentally shown that both V/sub th/ and the channel dopant number n/sub a/ distributions are given as the Gaussian function, and verified that the standard deviation of n/sub a/, can be expressed as the square root of the average of n/sub a/, which is consistent with statistics. In this study, it has been shown that V/sub th/ fluctuation (/spl delta/V/sub th/) is mainly caused by the statistical fluctuation of the channel dopant number which explains about 60% of the experimental results. Moreover, we discuss briefly a new scaling scenario, based on the experimental results of the channel length, the gate oxide thickness, and the channel dopant dependence of /spl delta/V/sub th/. Finally, we discuss V/sub th/ fluctuation caused by the independent statistical-variations of two different dopant atoms in the counter ion implantation process.< >21:T503,The use of nonionizing energy loss (NIEL) in predicting the effect of gamma, electron, and proton irradiations on Si, GaAs, and InP devices is discussed. The NIEL for electrons and protons has been calculated from the displacement threshold to 200 MeV. Convoluting the electron NIEL with the slowed down Compton secondary electron spectrum gives an effective NIEL for CO/sup 60/ gammas, enabling gamma-induced displacement damage to be correlated with particle results. The fluences of 1 MeV electrons equivalent to irradiation with 1 Mrad(Si) for Si, GaAs, and InP are given. Analytic proton NIEL calculations and results derived from the Monte Carlo TRIM agree exactly, as long as straggling is not significant. The NIEL calculations are compared with experimental proton and electron damage coefficients using solar cells as examples. A linear relationship is found between the NIEL and proton damage coefficients for Si, GaAs, and InP devices. For electrons, there appears to be a linear dependence for n-Si and n-GaAs, but for p-Si there is a quadratic relationship which decreases the damage coefficient at 1 MeV by a factor of approximately 10 below the value for n-Si.< >22:T455,One of the most important degradation modes in CMOS technologies, the bias temperature instability (BTI) has been known since the 1960s. Already in early interpretations, charge trapping in the oxide was considered an important aspect of the degradation. In their 1977 paper, Jeppson and Svensson suggested a hydrogen-diffusion controlled mechanism for the creation of interface states. Their reaction–diffusion model subsequently became the dominant explan

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