Impact of buffer charge on the reliability of carbon doped AlGaN/GaN-on-Si HEMTs

Charge trapping and transport in the carbon doped GaN buffer of an AlGaN/GaN-on-Si high electron mobility transistor (HEMT) have been investigated. Back-gating and dynamic Ron experiments show that a high vertical leakage current results in significant long-term negative charge trapping in the buffer leading to current collapse under standard device operating conditions. Controlling current-collapse requires control of not only the layer structures and its doping, but also the precise balance of leakage in each layer.