Thermally induced failure in GaAs transistors exposed to alpha particle irradiation

The response of a MESFET and an inverted HEMT to the impact of an alpha particle has been calculated by means of the Monte Carlo particle model, a technique for solving the Boltzmann transport and Poisson field equations self-consistently in space and time. The calculations show that all the terminals of the MESFET react by generating an initial current pulse followed by another; the timing of the second pulse depends on the angle of incidence of the alpha particle. The lattice heating rate was found to be largest at the corners of the ohmic contacts. The HEMT, on the other hand, hardly reacts electrically to the alpha particle but is more likely to burn out in an alpha particle radiation environment because of the larger lattice heat generation taking place in the interior of the transistor. The results also support the theory of the hot-electron induced subsurface catastrophic failure mechanism.