Low‐temperature dc characteristics of S‐ and Si‐doped Ga0.51In0.49P/GaAs high electron mobility transistors grown by metalorganic molecular beam epitaxy

Ga0.51In0.49P/GaAs high electron mobility transistors (HEMTs) grown by metalorganic molecular beam epitaxy have been fabricated for the first time. The typical transconductance (gm) of devices of 1.3‐μm gate length at 300 K is 110 mS/mm and is independent of donor type. At 100 K the dc characteristics of Si‐doped devices remain almost unchanged, while there is a decrease of 55% in gm and in the drain‐source saturation current (Idss) of the S‐doped devices. The degradation of the S‐doped HEMTs is attributed to ‘‘DX‐like’’ centers in the doped GaInP layer. All of the doped samples are characterized by a deep electron trap with an activation energy that takes values in the range 310–345 meV and causes persistent photoconductivity (PPC) in S‐doped samples, while Si doping suppresses the PPC effect.