High Performance Flexible Visible-Blind Ultraviolet Photodetectors with Two-Dimensional Electron Gas Based on Unconventional Release Strategy

Abstract

Interdigitated photodetectors (IPDs) based on the twodimensional electron gas (2DEG) at the AlGaN/GaN interface have gained prominence as high sensitivity ultraviolet (UV) PDs due to their excellent optoelectronic performance. However, most 2DEG-IPDs have been built on rigid substrates, thus limiting the use of 2DEG-IPDs in flexible and wearable applications. In this paper, we have demonstrated high performance flexible AlGaN/GaN 2DEG-IPDs using AlGaN/GaN 2DEG heterostructure membranes created from 8 in. AlGaN/GaN on insulator (AlGaN/GaNOI) substrates. The interdigitated AlGaN/GaN heterostructure has been engineered to reduce dark current by disconnecting the conductive channel at the heterostructure interface. Photocurrent has been also boosted by the escaped carriers from the 2DEG layer. Therefore, the utilization of a 2DEG layer in transferrable AlGaN/ GaN heterostructure membranes offers great promises for high performance flexible 2DEG-IPDs for advanced UV detection systems that are critically important in myriad biomedical and environmental applications.

Non‐Ultrawide Bandgap Semiconductor GaSe Nanobelts for Sensitive Deep Ultraviolet Light Photodetector Application

“…The lowest NEP and the highest D* are calculated to be 1.51 × 10 −15 W Hz −1/2 and 6.01 × 10 11 Jones, respectively, demonstrating the ability to detect a weak light signal (Figure S5, Supporting Information). It is worth noting that the present GaSe nanobelt displays much better photoelectric performance than previously reported GaSe nanosheet, including mechanically exfoliated GaSe nanosheets [ 20,39 ] and gas‐phase grown GaSe nanosheets, [ 40 ] which is comparable to or even better than that of traditional UWBG DUV photodetectors [ 12–15 ] (shown in Table 1 ), making it a promising candidate for application in future high‐performance DUV photodetector‐based devices and systems.…”

“…Currently, commercially available DUV photodetectors (e.g., photomultiplier tubes and Si photodetectors) normally operate at high bias voltage or adopt elaborate filters to eliminate the effect of visible and near infrared spectra. [ 10,11 ] To overcome the drawbacks of high power consumption as well as costly and complicated fabrication, a variety of ultrawide‐bandgap (UWBG) semiconductors with bandgaps larger than 3.4 eV (the bandgap of GaN), such as Al x Ga 1–x N, [ 12 ] Zn x Mg 1–x O, [ 13 ] Ga 2 O 3 , [ 14 ] and diamond, [ 15 ] have been extensively explored. Various studies have shown that their relatively high radiation hardness and intrinsic visible blindness have indeed made them prominent candidates for highly sensitive DUV photodetection applications.…”

Distinct UV–Visible Responsivity Enhancement of GaAs Photodetectors via Monolithic Integration of Antireflective Nanopillar Structure and UV Absorbing IGZO Layer

“…Light intensity was fixed at 1.2 mW. Responsivity ( R ) was calculated using the following equation [ 41–44 ] where I light is the photocurrent, I dark is the dark current, P λ is the incident light power density (0.95 mW mm −2 ), and S is the illumination area. Figure 4c shows the spectral responsivity of four devices measured under UV–visible lights from 300 to 800 nm.…”

“…Apart from optical performance, we also investigated the mechanism of the carrier transport process of the IGZO/GaAs nanopillar heterostructure photodetectors. Figure a–d shows the light intensity dependent photocurrent of Schottky and heterostructure photodetectors by varying the light intensities from 7.9 to 78.7 mW cm −2 at −5 V. The measured photocurrent was fitted by the power law as following [ 41,51 ] where C is a constant, θ is the empirical coefficient, I light is the photocurrent and P λ is the incident light power density. θ values can be extracted by using the linear fitting as indicated in Figure 6a–d.…”

“…θ<1 suggests trap‐assisted carrier transport, while θ>1 indicates photocurrent gain mechanism. [ 41,52 ] For the Schottky photodetector made on planar GaAs (Planar Schottky, Figure 6a), θ was 1.01 and 1.14 for 300 nm and 600 nm illumination, respectively, indicating that traps had little effect on the carrier transport under 300 nm illumination, while photocurrent gain occurred under 600 nm illumination. For the Schottky photodetectors made on GaAs nanopillar array (Nanopillar Schottky, Figure 6b), θ was 0.42 and 1.09 for 300 nm and 600 nm illumination, respectively, which were much smaller than those of the planar GaAs case (Figure 6a), indicating the stronger influence of surface states originated from MacEtch which act as traps to photocarriers.…”