Local increase in compressive strain (GaN) in gate recessed AlGaN/GaN MISHFET structures induced by an amorphous AlN dielectric layer

We fabricated and characterized metal insulator semiconductor (MIS) structures by applying amorphous AlN thin layers as a dielectric in gate recessed AlGaN/GaN heterostructure field effect transistors (HFETs). Micro photoluminescence measurements performed on MISHFET devices reveal a local non-uniform distribution of strain in the source-gate recess-drain region. Furthermore, a reduction of compressive stress up to 0.3 GPa in GaN after gate recessing was experimentally determined. The local stress increases by similar to 0.1 GPa and similar to 0.2 GPa after the deposition of 4 and 6 nm thin AlN layers in the gate recessed structures, respectively. Additionally, an increase in sheet charge density in the devices under investigation from similar to 3.8 x 10(12) cm(-2) to 6.2 x 10(12) cm(-2) was evaluated by capacitance-voltage measurements. Therefore, strain engineering by applying amorphous AlN layers in gate recessed MISHFETs can significantly improve their device characteristics.