High temperature dependence of the density of two-dimensional electron gas in Al_(0.18)Ga_(0.82)N/GaN heterostructures

摘要

Temperature dependence of the density of two-dimensional electron gas (2DEG) in Al_(0.18)Ga_(0.82)N/GaN heterostructures has been investigated by means of high temperature Hall measurements ranging from room temperature to 500℃. It is found that the 2DEG density decreases with increasing temperature in the range from room temperature to 250℃, and then increases with the temperature above 250℃. It is thought that the decrease of the 2DEG density from room temperature to 250℃ is caused by the reduction of the conduction band offset at high temperatures. The increase of measured 2DEG density at higher temperatures is attributed to the background electron concentration in the GaN layer. Theoretical calculation of the 2DEG density in Al_(0.18)Ga_(0.82)N/GaN heterostructures at various temperatures is consistent with the experimental results using the multilayer Hall effect model.