High‑performance n – Si/p – SeO2 /p – SiO2 heterojunction photodetectors for potential application in visible light communication technology

Abstract

Photodetectors suitable for visible light communication (VLC) technology were fabricated and characterized in this study. The photodetectors were designed using two p-type stacked layers of SeO2 and SiO2, which were coated onto n− type Si thin wafers. These stacked layers were deposited in a vacuum medium under a pressure of 10– 5 mbar using the thermal evaporation technique. p-SiO2 thin layer enriched the hole concentration of p-SeO2 layer forming p+n type heterojunction and prevented SeO2 from environmental contaminations. The microstructure, surface morphology, and photoelectrical properties of the n-Si/p-SeO2/p-SiO2 (SSS) detectors were explored. It was observed that the SSS detectors exhibited biasing and light power dependent asymmetry. The asymmetry varied in the range of 77–178 as the light power increased from zero to 77 mW. In addition, the SSS photodetectors demonstrated a current responsivity, external quantum efficiency, and specific detectivity reaching values of 123 mA/W, 15.6%, and 1.3 × 1010 Jones, respectively. These values are considered adequate for VLC technology. Practical tests have shown that the device can transmit wireless square-wave pulses with frequencies up to approximately 10–100 kHz. The growth and decay response times were found to be 1.15 ms and 0.89 ms, respectively. The features of the SSS detectors make them suitable for use as light-controlled current rectifiers and VLC detectors.