A Low-Power Silicon-on-Insulator Photodetector with a Nanometer-Scale Wire for Highly Integrated Circuit

Abstract

A highly sensitive photodetector, which is fabricated on a silicon-on-insulator metal oxide semiconductor field-effect transistor (SOI MOSFET) with a nanometer-scale wire, is proposed and optical responses are studied. Experimental results show that our device has a responsivity of 36 A/W, which is significantly higher than that of the conventional SOI MOSFET, and a significantly lower dark current. Interestingly, the photodetector with wire also shows pseudo kinks in a fully depleted type. We consider that these phenomena are affected by the wire, and the physical mechanism of the operation of our photodetector is explained by a strong lateral bipolar action. The linearity with optical power and spectral response in the visual spectral range are presented. Our device can be easily downscaled below 0.1 µm without the loss of sensitivity and the increase in dark current.

Nanowire Photodetectors

“…In most of the cases, these devices have shown large photoconductive gain which saturates at high irradiation intensities. 45 Typical rise and decay times in intrinsic NWs are less than 100 s, but they greatly increase with doping due to the formation of midgap states created by defects in the crystalline structure. 44 The photoresponse depends significantly on the device geometry and contacts; Schottky-like contacts to the NWs can lead to a spatial dependence of the photoresponse, with higher sensitivity near the contacts (see also Section 2.1).…”

Junction-less phototransistor with nanowire channels, a modeling study

“…4 VG primary = 1.0V, VS = 0.5V, VD = 0V, Intensity = 10 −4 W/cm 2 . 5 First two rows: VG secondary = −1.0V; third row VG secondary = −2.0V.…”

“…The small size of nanowires limits their ability to absorb light efficiently [3].Therefore, individual nanowires are preferred to be incorporated in photodetector geometries with optical gain, such as phototransistors. The transistor can be a conventional junction bipolar or a Metal Oxide Semiconductor (MOS) type [4,5], or even a junction-less geometry [6].…”

High-Gain Multiple-Gate Photodetector With Nanowires in the Channel

“…The channel is 500 nm wide; other dimensions and doping profiles of SOI-MOS are similar to those of NWN. The main reason for choosing SOI-MOS as the control is that it generates the largest amount of photocurrent among the family of single-gate phototransistors with the same channel length, and channel width of less than 500 nm [13].…”

“…Furthermore, there is a solution to compensate the poor absorption of NWs by incorporating the wires into gain-producing devices like avalanche photodiodes [12], photoconductors [7], and phototransistors [9], [13]. These devices [7], [9], [13] are fabricated on silicon-on-insulator (SOI) wafers, as the thin silicon layer facilitates creation of NWs. The device is normally planar: A phototransistor, for example, is similar to metal-oxide-semiconductor (MOS) structures.…”