Comparative investigation of gate leakage current in single and double channel InP HEMT

The InP HEMT is a key electron device for monolithic optoelectronic integration. However, the additional gate current due to impact ionization in the low band-gap InGaAs channel is a serious limitation for photoreceiver applications and for high breakdown voltage. In order to overcome this limitation InGaAs/InP double channel HEMTs (DC HEMT) have been fabricated, characterised and compared with InGaAs single channel HEMTs (SC HEMT). As expected the gate leakage current is much lower for the DC HEMT. A physical quasi-2D simulation supports this improved behaviour and shows that the gate leakage current peak is about four orders of magnitude lower for the DC HEMT than for the SC HEMT. This is verified for different gate lengths, even though the drain current for the DC HEMT is two times higher than that of the SC HEMT.