High-performance silicon nanowire bipolar phototransistors

Abstract

Silicon nanowires (SiNWs) have emerged as sensitive absorbing materials for photodetection at wavelengths ranging from ultraviolet (UV) to the near infrared. Most of the reports on SiNW photodetectors are based on photoconductor, photodiode, or field-effect transistor device structures. These SiNW devices each have their own advantages and trade-offs in optical gain, response time, operating voltage, and dark current noise. Here, we report on the experimental realization of single SiNW bipolar phototransistors on silicon-on-insulator substrates. Our SiNW devices are based on bipolar transistor structures with an optically injected base region and are fabricated using CMOScompatible processes. The experimentally measured optoelectronic characteristics of the SiNW phototransistors are in good agreement with simulation results. The SiNW phototransistors exhibit significantly enhanced response to UV and visible light, compared with typical Si p-in photodiodes. The near infrared responsivities of the SiNW phototransistors are comparable to those of Si avalanche photodiodes but are achieved at much lower operating voltages. Compared with other reported SiNW photodetectors as well as conventional bulk Si photodiodes and phototransistors, the SiNW phototransistors in this work demonstrate the combined advantages of high gain, high photoresponse, low dark current, and low operating voltage. Published by AIP Publishing.

Visible light–gated reconfigurable rotary actuation of electric nanomotors

“…It is known that, for semiconductors, photon excitation can generate additional free charge carriers, resulting in additional electrical conductivity, the so-called photoconductivity. Previous studies show that Si nanowires have strong photon response (33,34), where the increase of electrical conductivity can reach several orders of magnitude. When we monotonically increase the electrical conductivity of Si from 1 × 10 −3 S m −1 to 1 S m −1 , the peaks of both the cofield and counterfield rotations blue-shift, and the magnitudes of both increase substantially (Fig.…”

A Review on the Recent Progress of Silicon‐on‐Insulator‐Based Photodetectors

“…Such a relatively thin top silicon layer results in quite low light absorption in the SOI based photodetector. To improve the quantum efficiency and hence the responsivity expected in advanced SOI photodetector, devices with high internal gain have been demonstrated using bipolar junction transistors, [43] junction field effect transistors (JFETs), [44] metal-oxide-semiconductor field-effect transistor (MOSFETs) and gate-body tied MOSFETs. [45][46][47] Lately, a novel interface-coupled photodetector (ICPD) based on the coupling between the front and back interfaces of the SOI film was proposed and demonstrated.…”

High‐Efficiency Silicon Nanowire Array Near Infrared Photodetectors via Length Control and SiOx Surface Passivation

“…The peak responsivities around 1100 nm could be attributed to the higher photogain at longer wavelength as described in the other work. [ 45 ] The responsivity for the SiO x passivated photodetectors return back to the original responsivity spectrum after removing the SiO x layer (Figure S4d, Supporting Information). Despite the high dark current after the SiO x surface passivation, the responsivity spectrum shows the peak responsivity (0.55 A W −1 ) at 1100 nm.…”

“…In contrast, the responsivity is significantly enhanced for the 1 and 2 µm NW length photodetectors after the SiO x surface passivation due to the strong built‐in electric field in the surface region (Figure 5a,b). [ 45 ] The 1 µm NW length shows the responsivity of 0.51 A W −1 at 1100 nm, which is improved by 13 times compared with the one before the SiO x passivation. For the 2 µm NW length, the peak responsivity of 0.38 A W −1 is obtained at 1110 nm.…”