Threshold Voltage Instability of GaN HEMTs with Thin Barrier AlGaN Technology

In this work, the effect on threshold voltage (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf>) instability of AlGaN barriers using higher aluminum concentrations (29%) but only 5 nm will be discussed and compared to enhancement-mode (E-mode) devices using the gate recess process. The devices exhibit varying degrees of threshold voltage shift in the positive bias stress (PBS) test and the negative bias test (NBS) test. From the results, the FEGHEMTs were able to have better V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> stability in the presence of PBS. In the case of NBS, the negative V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</inf> influence will lose the electrons stored in the charge trap layer and cause the V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> to be shifted more.