Silicon nanowire core-shell PN junction phototransistors by self-assembled monolayer doping
- 8 May 2020
- journal article
- research article
- Published by IOP Publishing in Nanotechnology
- Vol. 31 (19), 195201
- https://doi.org/10.1088/1361-6528/ab6ea7
Abstract
Nanoscale photoconductors often have extremely high gain in quantum efficiency but suffer from the difficulty to design the density of surface states that cause the high photogain. In this Letter, we created high-gain photoconductors by forming a core-shell PN junction in silicon nanowires via self-assembled molecular monolayer doping. The highly doped n-type shell deactivates all the surface states by filling with electrons so that the n-type shell as a well, instead of the surface states, captures and emits photogenerated minority electrons under ON/OFF light illumination. The corresponding excess majority holes are accumulated in the nanowire channel and thus modulate the channel width, resulting in the experimentally observed high photogain (similar to 10(8)). The photoresponses of these phototransistors were systematically investigated as a function of the nanowire width and light illumination intensity. The results show that the nanowire channel is pinched off for the nanowires narrower than 73 nm due to the core-shell PN junction. We further derived analytical equations based on the PN junction device principle, finding the explicit gain equation that governs the photogain as a function of light intensity and other physical parameters of the nanowires. The explicit gain equations can fit well with the experimental data and allow us to design the core-shell nanowire phototransitors with desired performance.Funding Information
- National Natural Science Foundation of China (61874072)
This publication has 20 references indexed in Scilit:
- A Photoconductor Intrinsically Has No GainACS Photonics, 2018
- Dynamics of Charge Carriers in Silicon Nanowire Photoconductors Revealed by Photo Hall Effect MeasurementsACS Nano, 2018
- High-performance silicon nanowire bipolar phototransistorsApplied Physics Letters, 2016
- Gate Controlled Photocurrent Generation Mechanisms in High-Gain In2Se3 PhototransistorsNano Letters, 2015
- Diameter-Controlled and Surface-Modified Sb2Se3 Nanowires and Their Photodetector PerformanceScientific Reports, 2014
- High Responsivity Photoconductors Based on Iron Pyrite Nanowires Using Sulfurization of Anodized Iron Oxide NanotubesNano Letters, 2014
- Effects of electrical contacts on the photoconductive gain of nanowire photodetectorsApplied Physics Letters, 2011
- Diameter-Dependent Internal Gain in Ohmic Ge Nanowire PhotodetectorsNano Letters, 2010
- High-gain photoconductivity in semiconducting InN nanowiresApplied Physics Letters, 2009
- ZnO Nanowire UV Photodetectors with High Internal GainNano Letters, 2007