Photoresponse of an oxide semiconductor photosensor

Abstract

The authors investigated the photoresponse of a double-layer oxide semiconductor (GaInZnO–InZnO) thin-film transistor (TFT) under illumination, where the photocurrent in the negative gate bias region increased significantly without a negative shift in the threshold voltage. In particular, in the forward gate bias sweep direction (from −VG to +VG), the hysteresis of the transfer curves of the photosensor TFT became pronounced when the negative gate bias and its duration were increased. Additionally, the photocurrent level of the TFT remained almost the same as the level measured using a DC reverse gate bias sweep mode (from +VG to −VG). An analysis of the transfer curves, capacitance–voltage curves, and energy band diagrams indicates that the hysteresis characteristics can be explained by the competing effects of electrical-stress-induced defect generation and the screening of the negative gate bias by doubly positively charged oxygen vacancies depending on the gate bias polarity. In particular, the origin of the photoresponse of the photosensor TFT under illumination was studied intensively by qualitative analysis.

Oxide Semiconductor Phototransistor with Organolead Trihalide Perovskite Light Absorber

“…Amorphous indium gallium zinc oxide (IGZO) has become an attractive channel material in high performance thin film transistors (TFT), due to its advantageous features such as high field‐effect carrier mobility and low temperature large area processing capabilities. There is an ongoing effort to develop active matrix imager arrays and new touch screen technology integrating with either IGZO TFT backplane or IGZO based phototransistors . For photodetection and image sensing application, although currently amorphous silicon (a‐Si:H) has been widely adopted as image sensing materials, the low‐mobility nature of a‐Si:H has limited its application in high frame rate imaging, which is especially important in medical diagnosis application.…”

Microsecond Pulse I–V Approach to Understanding Defects in High Mobility Bi-layer Oxide Semiconductor Transistor

“…For high pixel-density, high-frame-rate, and large-area display back panels, TFTs should have high transistor mobility (over 10–30 cm 2 /V·s) 8–15 . Among various oxide semiconductors, double-layer heterojunction structures composed of a high-reliability front channel and a high-mobility back channel (or the reverse structure) have been studied to achieve high mobility while easing the trade-offs among mobility, initial threshold voltage, and reliability characteristics 13–21 . Use of heterojunction oxide semiconductors is a cost-effective strategy in comparison to finding new composite materials 22, 23 .…”

P‐8: Photocurrent Characteristics of Amorphous MgInO Thin Film Transistors

“…That is because holes have a rather lower mobility and larger effective mass compared to electrons. Therefore holes need more time and negative V gs assistant to drift to the interface and the source region [10]. The drain current in the depletion state under reverse sweep can be approximately described by the following equation [14],…”

“…For the forward sweep, electrons drift to the back channel. Holes drift to the front channel and accumulate at the source region under the electric field, which causes the source-to-channel potential barrier lowering (SBL) by Δɸ light [10][11][12][13]. The drain current under negative gate voltage originates from two sources.…”