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CARRIER TRANSPORT MECHANISM OF CdSexS1-x/Si HETEROJUNCTION

Iqbal S. Naji

n-type CdSexS1-x thin films of 500nm thickness with various Se content (0, 0.4, 0.8 ,& 1) were deposited on monocrystalline p-type Si (111) substrate at room temperature with rate equals to 9.25 A/sec by thermal evaporation technique. The effect of compound concentration (Se content) on the electrical properties of CdSexS1-x/Si heterostructure diodes was studied. The capacitance- voltage characteristic at frequency equal to 1 MHz revealed that these diodes are abrupt type, and the capacitance increases with increase Se content, while the width of depletion layer decreases. The current-voltage measurement for CdSexS1-x/Si diodes shows that the forward current at dark condition varies approximately exponentially with applied voltage and the mechanism of transport current coincide with diffusiontunneling model. The ideality factor decreases , while the tunneling constant increases with increasing Se content. The I-V measurements under illumination shows that the photocurrent increases with increasing Se content.