Effect of Metal-Semiconductor Contact Geometry on Electrical Properties of Al/ZnSe Thin Films

Abstract

The desire for smaller, more efficient and faster semiconductor devices has made design of metal-semiconductor contacts and characterization very vital. There is little research if any on the effect of metal-semiconductor contact geometry on I-V characteristics of ZnSe thin films. Various circular and rectangular thin filmed Al/ZnSe devices were designed by varying the shape and area of the Aluminium metal contact. Fabrication was done by thermal vacuum evaporation technique of zinc (99.99%) and selenium (99.99%) alloy powder onto masked glass slides using an Edward Auto 306 RF/DC magnetron evaporation chamber. Aluminium metal was subsequently deposited on the ZnSe thin films using circular and rectangular masks. Silver paste was used as the ohmic contacts. I-V characteristics were obtained using the Keithley 2400 source meter and data analyzed using Origin Software. From the J-V characteristic curves, the dark diode ideality factors ranged between 6.0 and 7.3 and were lower for circular Schottky devices than for rectangular ones. Device with circular Schottky contact area of 2.0423×10-4m2; a smaller inter-electrode spacing of 4mm had the lowest diode ideality factor of 6.361.