n-ZnO Based Nanostructure/p-Silicon Substrate Based Efficient p-n Heterojunction Diode

This paper reports the facile growth, characterization and efficient heterojunction diode application of well-crystalline aligned n-ZnO nanonails. The ZnO nanonails were grown on p-Silicon substrate by facile noncatalytic thermal evaporation process. Detailed morphological and structural studies revealed that the nanonails are grown in high density, possessing well-crystalline and wurtzite hexagonal phase. X-ray diffraction and Raman scattering confirm the wurtzite hexagonal phase structure whereas room-temperature photoluminescence studies affirms good optical properties for the as-grown nanonails. The as-grown aligned ZnO nanonails grown on silicon substrate are utilized to fabricate n-ZnO/p-Si heterojunction diode. The I V characteristics of the fabricated n-ZnO/p-Si heterojunction diode are studied at temperature <300 K and >= 300 K in the forward and reverse bias conditions. By detailed studies, it was found that the junction exhibits a diode-like behavior with a value of turn-on voltage of 5 V at almost all temperatures. The rectifying behavior of the fabricated heterojunction diode, at 5 V, is demonstrated by rectifying ratio of 4 at 77 K which decreases to 2 at 277 K. Moreover, the delivered current at this turn-on voltage is the least and in the order of similar to 1 mu A, at 77 K. This cur rent gradually increases to 6 pc,A which occurs, at the same turn-on voltage, when the temperature changes in the range of 77 <= T <= 277 K and drastically increases to similar to 400 mu A at 427 K while the rectifying ratio is dropped to similar to 0.4. For the reverse-bias voltage of 5 V, the leakage current changes from similar to 10(-7) A at 77 K to similar to 10(-3) A at 427 K. These results show that the turn-on voltage, breakdown voltage and leakage current have exhibited similar behavior in reverse bias due to the increase in temperature.