A ZnS0.07Se0.93 metal-semiconductor field effect transistor

We report the fabrication and test data for a n-ZnS_0.07Se_0.93 metal-semiconductor field effect transistor (MESFET). A ZnSSe FET could be a key element in opto-electronic integration employing light emitting devices, metal-semiconductor-metal photo-detectors (MSM-PD) and MESFET pre-amplifiers. Wide bandgap n-ZnS_0.07Se_0.93 is lattice-matched to the GaAs substrate and posses the “light hardness” property. A mesa active island was used to isolate devices. Source and drain (SID) ohmic contacts and gate Schottky contact were formed by Cr/In/Cr and Au, respectively. Recess etching and self-aligning techniques were adopted. Depletion mode FETs with varying gate width-to-length ratio of W/L=200 μm/20 μm, 200 μm/4 μm and 200 μm/2 μm were fabricated and the terminal parameters of a 2 μm FET are as follows: the turn-on voltage, V_on≈1.75 V, the pinch-off voltage, V_P≈13 V, the unit transconductance, g_m=8.73 mS/mm, and the breakdown voltage without a gate-drain bias, BV≈28 V