Characterization of p-SnO2:Al /n-ZnO:Al p-n junction deposited by spray pyrolysis technique for led applications
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Date
2015-06
Authors
Nyangaresi, Onkundi Paul
Journal Title
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Publisher
Kenyatta University
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 The band gap of the film was The band gap of the film was The band gap of the film was The band gap of the film was The band gap of the film was The band gap of the film was The band gap of the film was The band gap of the film was The band gap of the film was The band gap of the film was The band gap of the film was 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 a band gap of a band gap of a band gap of a band gap of a band gap of a band gap of a band gap of a band gap of a band gap of 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).
Description
A thesis submitted in partial fulfillment of the requirement for the award of the degree of master of science (electronics and instrumentation) in the school of pure and applied sciences of Kenyatta University.