Fabrication and characterization of a depletion-mode ZnS_0.07Se_0.93 MESFET

We report the fabrication and characterization of a depletion-mode n-channel ZnS_0.07Se_0.93 metal-semiconductor fiels effect transistor (MESFET). A ZnSSe FET could be a key element in opto-electronic integration consisting of light emitters, light receivers and MESFET pre-amplifiers. Mesa isolation, recess etching and self-alignment techniques were adopted to optimize the MESFET performance. Source and drain (S/D) ohmic contacts and gate Schottky contact were formed by Cr/In/Cr and Au deposition, respectively. Depletion mode FET'S with 200 μm/4 μm and 200 μm/2 μm were fabricated. A 2 μm FET was characterized as follows: the turn-on voltage, V_om ≈ 1.75 V, the pinch-off voltage, V_p ≈ -13 V, the unit transconductance, g_m ≈ 8.73 mS/mm, and the breakdown voltage with zero gate-source bias, BV ≈ 28 V.