Effects of oxygen pressure on n-ZnO/p-Si heterojunctions fabricated using pulsed laser deposition

Abstract

ZnO films were prepared on p-Si substrates using pulsed laser deposition (PLD) and n-ZnO/p-Si heterojunctions were fabricated at different oxygen partial pressures. The effects of oxygen pressures on crystallinity and surface morphology of ZnO films and the I–V characteristics of n-ZnO/p-Si heterojunctions were studied. It was found that the films grown in the oxygen pressure range from 10 −5–10 −2 Torr were all c-axis oriented. The surface morphologies were strongly dependent on the oxygen partial pressure. The current–voltage ( I– V) characteristics of the heterojunctions could be classified into two categories depending on the oxygen pressure. At low pressure (10 −5–10 −4 Torr), the I– V curves were similar to those of common p–n junctions. As the oxygen pressure increased to 10 −3 Torr, the I– V curves changed markedly. Based on the I– V characteristics, an energy band diagram of n-ZnO/p-Si was proposed.