Single-Crystalline All-Oxide α–γ–β Heterostructures for Deep-Ultraviolet Photodetection

Abstract

Recent advancements in gallium oxide (Ga2O3)-based heterostructures have allowed optoelectronic devices to be used extensively in the fields of power electronics and deep-ultraviolet (DUV) photodetection. While most previous research has involved realizing single-crystalline Ga2O3 layers on native substrates for high conductivity and visible-light transparency, presented and investigated herein is a single-crystalline β-Ga2O3 layer grown on an α-Al2O3 substrate through an interfacial γ-In2O3 layer. The single-crystalline transparent-conductive-oxide layer made of wafer-scalable γ-In2O3 provides the high carrier transport, visible-light transparency, and antioxidation properties that are critical for realizing vertically oriented heterostructures for transparent-oxide photonic platforms. Physical characterization based on X-ray diffraction and high-resolution transmission electron microscopy imaging confirms the single-crystalline nature of the grown films and the crystallographic orientation relationships among the monoclinic β-Ga2O3, cubic γ-In2O3, and trigonal α-Al2O3, while the elemental composition and sharp interfaces across the heterostructure are confirmed using Rutherford backscattering spectrometry.Furthermore, the energy-band offsets are determined using X-ray photoelectron spectroscopy at the β-Ga2O3/ γ-In2O3 interface, elucidating a type-II heterojunction with conduction-and valenceband offsets of 0.16 and 1.38 eV, respectively. Based on the single-crystalline β-Ga2O3/ γ-In2O3/ α-Al2O3 all-oxide heterostructure, a vertically oriented DUV photodetector is fabricated that exhibits a high photoresponsivity of 94.3 A/W, an external quantum efficiency of 4.6×10 4 % and a specific detectivity of 3.09×10 12 Jones at 250 nm. The present demonstration lays a strong foundation for and paves the way to future all-oxide-based transparent photonic platforms.

Comprehensively Improved Performance of β-Ga2O3 Solar-Blind Photodetector Enabled by a Homojunction with Unique Passivation Mechanisms

“…However, −3 dB cutoff wavelengths are located at around 266 nm for all the samples (Figure d), suggesting the SFP treatment introduced few subgap states as far as the whole bulk β-Ga 2 O 3 was concerned. As shown in Figure f and Table S1, sample-15 is highly competitive in terms of comprehensive properties as compared with the film-type Ga 2 O 3 PDs reported so far. ,− ,− …”

Ultrahigh Gain Solar Blind Avalanche Photodetector Using an Amorphous Ga2O3-Based Heterojunction

“…As shown in Figure b, the EQE value can reach ∼2.9 × 10 7 % at 40 V reverse bias, indicating that huge amount of carriers are efficiently excited in the Ga 2 O 3 /ITO heterojunction due to the avalanche effect. In addition to the EQE value, another key parameter of a PD is the detectivity ( D* ), which could be calculated using the following equation …”

A Strategic Review on Gallium Oxide Based Deep‐Ultraviolet Photodetectors: Recent Progress and Future Prospects

“…[206] Recently, single crystalline all-oxides-based β-Ga 38 eV, respectively. [207] The subsequent vertical PD fabricated with these heterostructures show a responsivity of 94.3 A W −1 and specific detectivity of 3.09 × 10 12 Jones at 250 nm and −5 V bias. Kumar et al in their work [208] on n-Ga 2 O 3 /p-CuO quasi-heterojunction based MSM PD boast of an ultrahigh responsivity of 6.33 × 10 3 A W −1 and an ultralow dark current of 6.94 fA.…”

“…[ 206 ] Recently, single crystalline all‐oxides‐based β‐Ga 2 O 3 /γ‐In 2 O 3 /α‐Al 2 O 3 heterostructures have been fabricated with the energy‐band offsets relating to the β‐Ga 2 O 3 /γ‐In 2 O 3 interface revealing a type‐II heterojunction with conduction band offset (CBO) and valence band offset (VBO) values of 0.16 and 1.38 eV, respectively. [ 207 ] The subsequent vertical PD fabricated with these heterostructures show a responsivity of 94.3 A W −1 and specific detectivity of 3.09 × 10 12 Jones at 250 nm and −5 V bias. Kumar et al.…”