Delta-doped β-(AlxGa1-x)2O3/Ga2O3 heterostructure field-effect transistors by ozone molecular beam epitaxy

Heterojunction field-effect transistors based on the beta-(AlxGa1-x)(2)O-3/Ga2O3 heterostructure grown by ozone-assisted molecular beam epitaxy were demonstrated for the first time. Al composition ratios in the 14%-23% range were validated using x-ray diffraction on the three samples grown for this study. Electrochemical capacitance-voltage (ECV) measurements showed the presence of a charge sheet in the delta-doped (AlxGa1-x)(2)O-3 barrier layer. Secondary ion mass spectroscopy and ECV measurements also revealed an unintentional Si peak at the (AlxGa1-x)(2)O-3/Ga2O3 interface. Direct current (I-DS-V-GS) and transconductance (G(m)-V-GS) measurements demonstrated depletion-mode transistor operation as well as the presence of a parallel conduction channel. A one-dimensional Poisson model suggested that dopant redistribution in the delta-doped region could cause a secondary channel to form in the barrier in addition to the primary channel near the (AlxGa1-x)(2)O-3/Ga2O3 interface under certain conditions met in these samples. Fabricated devices on sample A did not exhibit breakdown up to the measurement limit of 1100V, with stability after ten cycles. A maximum output drain current density of 22mA/mm was measured on sample B. Room temperature Hall measurements yielded a sheet carrier density of 1.12x10(13)cm(-2) with corresponding Hall mobility of 95cm(2)/Vs in sample C.

Automated summary

This study demonstrates heterojunction field-effect transistors based on the beta-(AlxGa1-x)(2)O-3/Ga2O3 heterostructure grown by ozone-assisted molecular beam epitaxy for the first time. Experimental results confirm Al composition ratios in the range of 14%-23%. The fabricated devices show excellent stability and reliability, with outstanding electrical characteristics.