Giant Photoresponsivity and External Quantum Efficiency in a Contact‐Engineered Broadband a‐IGZO Phototransistor

Abstract

Broadband photodetectors with a wide ultraviolet (UV)-visible (vis)-nearinfrared (NIR) spectral response reduce cost and form factors in smart sensing systems by using one rather than multiple devices for versatile applications. However, simultaneously achieving broadband detection, high responsivity, and fast response time remains challenging. This study demonstrates a highperformance broadband amorphous In-Ga-Zn-O (a-IGZO) phototransistor using an engineered Ni/Ti bilayer metal contact. This device differs drastically from the conventional a-IGZO phototransistors in several aspects: 1) Pronounced photoresponse occurs at the device ON-state rather than the OFF-state. 2) A broadband response of 385-980 nm rather than a narrowband UV response. 3) Fast sub-ms response time with no persistent photocurrent. 4) High responsivity of exceeding 10 5 A W −1 . The external quantum efficiency exceeding 10 7 % and specific detectivity exceeding 10 15 Jones are also among the best of any UV-vis-NIR broadband photodetectors. The photoresponse is attributed to the light-sensitive source-drain series resistance at the ON-state. The Ni diffusion during postmetal annealing induces photoactive subgap states and modulates the conductivity of a-IGZO at the contact region. The superior performance using low-temperature processes and simple device structures as the widely available a-IGZO technology suggests a tremendous application potential of this broadband phototransistor.

Highly Sensitive Hybrid Oxide Phototransistors with Photoresponsive Zeolitic‐Imidazolate‐Frameworks for Real‐Time Light Detection

“…[3,[6][7][8][9] Despite having a wide optical bandgap (E g ), these exhibit photosensitivity in the blue to UV range owing to the photoionization phenomenon induced by numerous oxygen vacancies (V O ) inside the channel materials of the Ph-TRs. [10][11][12] However, the generation of I ph from V O presents a disadvantage in operating oxide semiconductor Ph-TRs because of: i) a reduction in photosensitivity, ii) limitation of detectable wavelength range, and iii) slow response and recovery to light by persistent photocurrent (PPC). [13][14][15] Consequently, these issues limit the detection of light signals in various wavelength ranges, even though they have potential as optimal sensor devices.…”

Realization of Visible‐Light Detection in InGaZnO Thin‐Film Transistor via Oxygen Vacancy Modulation through N2 Treatments

“…[34] The maximum of the D* and the D* at V on (D*-V on ) are, respectively, shown in Figure 2c,d. The test results show that the D* of the device without N 2 annealing can be ignored, which are respectively 1.42 × 10 9 Jones at 700 nm, 1.34 × 10 9 Jones at The other two crucial optical parameters are external quantum efficiency (EQE) [35] and linear dynamic range (LDR). [31] The EQE characterizes the efficiency of converting photons into a stream of electrons, whereas LDR characterizes the linear response range of a photodetector.…”

Low-power driven broadband phototransistor with a PbS/IGO/HfO2 stack

“…19,20 The most studied channel materials in AOS-based phototransistors are amorphous indium-gallium-zinc oxide (IGZO) and zinc-oxide (ZnO). [21][22][23][24][25][26] However, their intrinsic large band gap (43 eV) allows for the detection of UV photons whereas visible light is hardly absorbed in AOS layer. [27][28][29] To offer a detection capability for visible light, a number of different absorption layers have been introduced into oxide TFTs, such as oxides, chalcogenides, organic materials, perovskites, and QDs.…”