Effects of Si δ-Doped Layer on an AlGaN/InGaN/GaN High Electron Mobility Transistor

The effects of a Si δ-doped layer on the electrical properties of an AlGaN/InGaN/GaN high electron mobility transistor (HEMT) are studied theoretically by Technology Computer-Aided Design (TCAD) in this paper. The Si δ-doped GaN layer which exists between the InGaN channel layer and the GaN buffer plays an important role in increasing the electron density in the channel. Because there is better electron confinement and higher electron density, the proposed device shows excellent performances in direct current (DC) and radio frequency (RF) characteristics. Compared to the traditional GaN and InGaN channel HEMTs, the peak transconductance in the proposed device is increased by 25 and 11%, and the maximum drain current is increased by 39 and 32%, respectively. From the value of subthreshold swing (SS) and drain-induced barrier lowering (DIBL), the proposed device shows almost the same ability to suppress the short-channel effect (SCE) as the traditional InGaN channel HEMT which is significantly better than GaN channel HEMT. In addition, the current gain cutoff frequency (f_T) of the proposed device is 26 and 7% higher than that of the traditional GaN and InGaN channel HEMT, and the maximum power gain cutoff frequency (f_max) is increased by 43 and 8%, respectively.