Polarization effects in nitride semiconductors and device structures

摘要

Wide bandgap nitride semiconductors have recently attracted a great level of attention owing to their direct bandgaps in the visible to ultraviolet regions of the spectrum as emitters and detectors. Moreover, this material system with its favorable heteroJunctions and transport properties began to produce very respect- able power levels in microwave amplifiers. If and when the breakdown fields achieved experimentally approach the predicted values, this material system would also be very attractive for power switching devices. In addition to the premature breakdown, high concentration of de- fects, and inhomogeneities, a number of scientific chal- lenges remain including a clear experimental investiga- tion of polarization effects. In this paper, following a succinct review of the progress that has been made, spontaneous and piezoelectric polarization effects and their impact on sample device-like hetero-structures will be treated.