Das Partha Pratim, Samanta Sudeshna, Wang Lin, Kim Jaeyong, Vogt Thomas, Devi P Sujatha, Lee Yongjae
Department of Earth System Sciences, Yonsei University Seoul 120749 Korea
Center for High Pressure Science and Technology Advanced Research Shanghai China.
RSC Adv. 2019 Feb 1;9(8):4303-4313. doi: 10.1039/c8ra10219h. eCollection 2019 Jan 30.
Control and design of native defects in semiconductors are extremely important for industrial applications. Here, we investigated the effect of external hydrostatic pressure on the redistribution of native defects and their impact on structural phase transitions and photoconductivity in ZnO. We investigated morphologically distinct rod- (ZnO-R) and flower-like (ZnO-F) ZnO microstructures where the latter contains several native defects namely, oxygen vacancies, zinc interstitials and oxygen interstitials. Synchrotron X-ray diffraction reveals pressure-induced irreversible phase transformation of ZnO-F with the emergence of a hexagonal metallic Zn phase due to enhanced diffusion of interstitial Zn during decompression. In contrast, ZnO-R undergoes a reversible structural phase transition displaying a large hysteresis during decompression. We evidenced that the pressure-induced strain and inhomogeneous distribution of defects play crucial roles at structural phase transition. Raman spectroscopy and emission studies further confirm that the recovered ZnO-R appears less defective than ZnO-F. It resulted in lower photocurrent gain and slower photoresponse during time-dependent transient photoresponse with the synergistic application of pressure and illumination (ultra-violet). While successive pressure treatments improved the photoconductivity in ZnO-R, ZnO-F failed to recover even its ambient photoresponse. Pressure-induced redistribution of native defects and the optoelectronic response in ZnO might provide new opportunities in promising semiconductors.
半导体中本征缺陷的控制和设计对于工业应用极为重要。在此，我们研究了外部静水压力对本征缺陷重新分布的影响及其对ZnO中结构相变和光电导率的影响。我们研究了形态上不同的棒状（ZnO-R）和花状（ZnO-F）ZnO微结构，其中后者包含几种本征缺陷，即氧空位、锌间隙原子和氧间隙原子。同步辐射X射线衍射揭示了ZnO-F在压力作用下发生不可逆相变，在减压过程中由于间隙锌扩散增强而出现六方金属Zn相。相比之下，ZnO-R经历可逆结构相变，在减压过程中表现出较大的滞后现象。我们证明了压力诱导的应变和缺陷的不均匀分布在结构相变中起关键作用。拉曼光谱和发射研究进一步证实，恢复后的ZnO-R的缺陷比ZnO-F少。在压力和光照（紫外线）协同作用下的时间相关瞬态光响应过程中，这导致了较低的光电流增益和较慢的光响应。虽然连续的压力处理提高了ZnO-R的光电导率，但ZnO-F甚至未能恢复其环境光响应。压力诱导的本征缺陷重新分布和ZnO中的光电响应可能为有前景的半导体提供新的机遇。
