Characterization of Impact Ionization Coefficient of ZnO Based on a p-Si/i-ZnO/n-AZO Avalanche Photodiode

Abstract

The avalanche photodiode is a highly sensitive photon detector with wide applications in optical communication and single photon detection. ZnO is a promising wide band gap material to realize a UV avalanche photodiode (APD). However, the lack of p-type doping, the strong self-compensation effect, and the scarcity of data on the ionization coefficients restrain the development and application of ZnO APD. Furthermore, ZnO APD has been seldom reported before. In this work, we employed a p-Si/i-ZnO/n-AZO structure to successfully realize electron avalanche multiplication. Based on this structure, we investigated the band structure, field profile, Current–Voltage (I-V) characteristics, and avalanche gain. To examine the influence of the width of the i-ZnO layer on the performance, we changed the i-ZnO layer thickness to 250, 500, and 750 nm. The measured breakdown voltages agree well with the corresponding threshold electric field strengths that we calculated. The agreement between the experimental data and calculated results supports our analysis. Finally, we provide data on the impact ionization coefficients of electrons for ZnO along the (001) direction, which is of great significance in designing high-performance low excess noise ZnO APD. Our work lays a foundation to realize a high-performance ZnO-based avalanche device.

Influence of the AZO Electrode on ZnO Nanowire Growth by PLI-MOCVD and Related Piezoelectric Performance: Implications for Mechanical Energy Transducers

“…39 Similarly, Pradel et al demonstrated that the piezoelectric output was significantly increased by two ZnO layers containing different dopants. 40 The p-Si/ZnO/n-AZO heterostructure was also demonstrated by Li et al 41 In our work, a P-N junction formed between the p-doped Si-substrate and the ZnO NWs could lead to a higher piezoelectric amplitude compared to ZnO/AZO junction, but the present experimental results show the opposite trend. The other factor that could also affect the results is the dimensions of NWs.…”

Editorial for the Special Issue on Miniaturized Silicon Photodetectors: New Perspectives and Applications

“…This work shows that, by adjusting the C/Si ratio, the quality of the 4H-SiC epilayer can be improved and the performance of the Ni/4H-SiC Schottky detector increased. In their work, G. Li et al evaluate the impact ionization coefficient of electrons in a ZnO layer along the (001) direction [ 12 ]. In order to do it, the authors have investigated p-Si/i-ZnO/n-AZO structures illuminated by a 532 nm laser diode where the electron avalanche multiplication is triggered in the i-ZnO layer whose thickness was varied from 250 to 750 nm.…”