Analysis of gate leakage on MOVPE grown InAlAs/InGaAs-HFET

The leakage of reverse biased Schottky gates on lattice matched InAIAs/InGaAs HFET grown by MOVPE on s.i. InP subtsrates is adressed. The contribution of (i) (thermionic-) field emission across the Schottky barrier (ii) generation-recombination in the space charge region and (iii) impact ionization with subsequent hole tunneling are identified by means of their temperature dependence. Taking the overall importance of the gate to channel potential into account we will show that the leakage in biased HFET with a doping level ND ≪ 4*10¹⁸cm^-3 is dominated by impact ionization.