A quantum well δ-doped GaAs FET fabricated by low-pressure metal organic chemical vapor deposition

Abstract

A quantum well δ-doped n-type GaAs layer with Ga source open has been grown successfully by the low-pressure metal organic chemical vapor deposition (LP-MOCVD). The measured capacitance-voltage profile shows that a sheet-doping concentration up to 5 × 10 12 cm −2 for the δ-doped GaAs layer can be easily achieved. The full-width at half-maximum (FWHM) is quite narrow. From the Hall measurement, the electron mobility increases inversely proportional to the δ-doping concentration. An enhanced mobiity can be obtained more than 2300 and 4300 cm 2/Vs with doping concentration of 5.0 × 10 18 cm −3 at 300 and 77 K, respectively. Based on this technique, a quantum well δ-doped GaAs FET has been fabricated and demonstrated. With a gate geometry of 5 × 250 μm 2 and doping concentration of 5.9 × 10 18 cm −3, the estimated transconductance of the δ-doped FET is 64 mS/mm. Since there is an undoped GaAs layer grown on the top of the δ-doped sheet, the breakdown voltage can be increased significantly (> 17 V). Furthermore, the saturation current density can be obtained higher than 110 mA/mm.