Material, Structural Optimization and Analysis of Visible-Range Back-Illuminated OPFET photodetector

Abstract

High gain-bandwidth product and visible/UV contrast photodetectors are vital in Visible Light Communication (VLC) and Ultraviolet (UV) reflectance imaging applications respectively. We adopt material and structural optimization to perceive such photodetectors with back-illuminated Optical Field Effect Transistor (OPFET) wherein any potential difference in absorption coefficient of the semiconductor material between the visible and the UV range (higher in the UV region) can be explored at its full potential. The results have been analyzed using the photoconductive and the photovoltaic effects, the series resistance effects, scaling rules-induced effects, and channel length-variation effects. We consider the three most prominent and functional materials in the visible range (Si, GaAs, and InP) for material-based optimization. Structural optimization is performed employing a range of medium gate lengths. The gate electrodes utilized are Indium-Tin-Oxide (ITO) for Si and GaAs with high Schottky barrier heights of ~0.71 eV and ~0.98 eV respectively whereas the Schottky contact on InP is gold (Au) with a high barrier height of ~0.8 eV. The operating visible and UV wavelengths are 600 nm and 350 nm respectively. The results suggest that GaAs OPFET has wide bandwidth potential in the gigahertz range apart from its high sensitivity and visible/UV contrast features. The InP-based OPFET exhibits high sensitivity and sub-gigahertz frequency response; and can compete or surpass the GaAs OPFET in terms of the visible/UV contrast ratio. The Si OPFET shows bandwidth in the megahertz range along with high sensitivity but exhibits low contrast ratio. The structural parameters have a significant effect on the detector response. The results are in-line with the experiments. This paper reflects the performance of the investigated detectors towards the said applications through optimization and the associated analysis represents the dependence of the obtained response on the device material and structural parameters, thus, opening the door for further research.

Optical dynamics at the MoO3/ZnPc interfaces prepared for visible light communications

“…1 1 when irradiated with light source of 600 nm and with 350 nm, the data transfer in the megahertz range was possible [24]. Based on these examples, it is possible to think that in accordance with the optical conductivity parameters listed in table 1, the MoO 3 /ZnPc appears to be promising interfaces for use in visible light communications.…”

“…It is also clear from figure 6(a) that the laser illuminated device, whose experimental setup is presented in the inset of figure 6(b), exhibit higher current values compared to the dark current (I D ). The increase in the current under light illumination (I L ) is more pronounced under reverse biasing conditions owing to the high generation rates which is setup under reverse biasing conditions compared to the recombination rates that dominates under forward biasing [18,24]. The light photosensitivity (S = I I L D / ) which is presented in figure 6(b) increases significantly with increasing reverse biasing voltage.…”

Analysis of Wide-Bandgap Material OPFET UV Detectors for High Dynamic Range Imaging and Communication Applications

“…To ad-dress these issues, a photo FET device viz. Optical Field Effect Transistor (OPFET) or optically-controlled Metal-Semiconductor Field Effect Transistor (MESFET) is suggested, which has so far delivered high gain and moderately high bandwidth [6]- [11]. The performance can be further improved through optimization.…”

“…Although there has been significant research on MESFET-based photodetectors, optically-controlled amplifiers, oscillators, switches, and mixers, over the past few decades, the research focused on GaAs as the semiconductor which primarily operates in the visible to near-infrared region [6]- [11]. Hardly any research has been carried out on the UV responses of OPFET detectors.…”