Characterization Of P-Sno2:Al /N-Zno:Al P-N Junction Deposited By Spray Pyrolysis Technique For Led Applications

Abstract

Thin films of SnO2:Al and ZnO: Al were deposited under different deposition parameters. Effect of substrate temperature, Carrier gas pressure, substrate to nozzle distance and doping percentages were investigated to obtain optimum conditions for deposition of p-SnO2:Al for LED applications. Optimized film of SnO2:Al was deposited at temperature of 408 o C, nozzle substrate distance of 4.75 cm, carrier gas pressure of 1.88 bars and aluminium doping atomic percent of 5.37 %. Solid spectrophotometer DUV 3700 was used to obtain the transmittance data that was between 75% - 78% in the visible range. Four point probe was used to obtain electrical resistivity of the films which was found to be of the order of 10-3 Ωcm. The band gap of the film was 3.96 eV. For n-ZnO: Al, deposition was done at a temperature of 400 o C, carrier gas pressure of 1.5 bars, nozzle substrate distance of 4.5cm. Aluminium doping atomic percent of 2.42 %. Solid spectrophotometer DUV 3700 was used to obtain the transmittance data. The average transmittance was found to be between 82% - 89% in the visible range. The films had resistivity of the order 10-1 Ωcm and a band gap of 3.71eV. The p-n junction of p-SnO2:Al and n-ZnO:Al that was fabricated had a turn-on voltage of 0.6V with a maximum current of 0.75μA at 4 V. These results show that films of p-SnO2:Al and n-ZnO:Al can be used in opto-electronic devices such as light emitting diodes (LEDs).