Temperature dependence of the current-voltage characteristics of metal-semiconductor field-effect transistors in n-type β-SiC grown via chemical vapor deposition

Abstract

Metal‐semiconductor field‐effect transistors (MESFET’s) have been fabricated in an unintentionally doped, n‐type β‐SiC thin film grown by chemical vapor deposition (CVD). This n‐type layer was deposited on a monocrystalline p‐type β‐SiC (100) CVD layer previously grown on a p‐type Si (100) substrate. The buried p layer allowed the devices to be fabricated several microns away from the SiC/Si interface region which contained numerous defects formed as a result of the poor lattice match and different coefficients of thermal expansion between SiC and Si. Thermally evaporated Au was utilized for the gate contact. Sputtered TaSi₂ was employed for the source and drain contacts. The gate lengths and channel depths of these MESFET’s were 3.5 and 0.60 μm, respectively. Saturation of the drain currents was achieved at room temperature. Furthermore, the current‐voltage characteristics, measured from 298 to 623 K for the first time, indicated that these MESFET’s performed reasonably well throughout this temperature range. The maximum transconductance obtained was 1.6 mS/mm; the value of this parameter decreased with temperature.