Voltage-Tunable UVC–UVB Dual-Band Metal–Semiconductor–Metal Photodetector Based on Ga2O3/MgZnO Heterostructure by RF Sputtering

Abstract

Dual-band metal–semiconductor–metal (MSM) photodetectors (PDs) with a Ga2O3/MgZnO heterostructure were fabricated by radio frequency (RF) sputtering, which can detect ultraviolet C (UVC) and ultraviolet B (UVB) bands individually by controlling different bias voltages. A PD with the annealing temperature of Ga2O3 at 600 °C can improve the crystal quality of Ga2O3 thin film and exhibit the least persistent photoconductivity (PPC) effect. However, a PD with the annealing temperature of Ga2O3 at 600 °C cannot achieve a voltage-tunable dual-band characteristic. On the contrary, the PD without annealing can suppress the carriers from the bottom layer of MgZnO thin film at a lower bias voltage of 1 V. At this time, the peak responsivity at 250 nm was mainly dominated by the top layer of Ga2O3 thin film. Then, as the bias voltage increased to 5 V, the peak detection wavelength shifted from 250 (UVC) to 320 nm (UVB). In addition, the PD with a 25 nm–thick SiO2 layer inserted between Ga2O3 and MgZnO thin film can achieve a broader operating bias voltage range for dual-band applications.

Solar‐Blind Ultrathin Sn‐Doped Polycrystalline Ga2O3 UV Phototransistor for Normally Off Operation

“…A low photoresponse is also observed in the range of 230-290 nm, which may be attributed to the polycrystalline and doping effects of Ga 2 O 3 , resulting in substate energy levels forming band absorption tails. [50][51][52][53][54] Figure 4b also shows that the photoresponse of the device is due to the β-Ga 2 O 3 film and is not related to the absorption of the Si substrate because the responsivity of Si increases for wavelengths above 350 nm. [38,56,[63][64][65][66][67][68][69][70][71][72][73] The gate voltages at which the highest PDCRs were observed are compared for various Ga 2 O 3 PDs, as shown in Figure 5.…”

“…[55] It has been reported that the grain boundaries in polycrystalline β-Ga 2 O 3 generate mid-gap defect levels within the energy bandgap, thereby serving as trapping/ de-trapping sites for the photogenerated carriers and causing the linear rise and decay. [53,54] The detectivity D* can be calculated using R and I dark in the same manner as previously reported, [35,[57][58][59] where we use the approximations to account for the shot noise and ignore the Johnson thermal noise. The detectivity can be expressed as D* ¼ R/(2qI dark ) 1/2 , where q is the fundamental unit of charge, and the detailed description is given in the Supporting Information (Equation S1-S3, Supporting Information).…”

“…[ 55 ] It has been reported that the grain boundaries in polycrystalline β ‐Ga 2 O 3 generate mid‐gap defect levels within the energy bandgap, thereby serving as trapping/de‐trapping sites for the photogenerated carriers and causing the linear rise and decay. [ 53,54 ]…”

High-performance (Al0.4Ga0.6)2O3/Al0.32Ga0.68N-based UVC/UVB tunable dual-band photodetectors

“…20,39 Therefore, the noise equivalent power (NEP) and specific detectivity D NEP * ð Þ are proposed to further assess the sensitivity of the PDs, which can be obtained from the equations: NEP ¼ ffiffiffiffiffi A performance comparison among the fabricated PDs and reported state-of-the-art PDs is summarized in Table 1. 25,26,40,41 Compared with PDs based on (Al x Ga 1−x ) 2 O 3 films with comparable Al content, the fabricated PDs have displayed a promising responsivity and detectivity with a superior EQE value over the UVC region. Besides, it is also worth highlighting that the PDs exhibit an appealing dualband detection capability that covers a broader UV band, benefiting from the designed bilayer structure.…”

Optical and Optoelectronic Studies of Binary and Ternary Films of Poly(L-Tryptophane), Poly(5-hydroxy-L-tryptophane), and P(TER-CO-TRI) Doped with Sudan Dye

“…As a result, finding a potential candidate for an organic composite to be used as the active layer of UV detectors is critical. Many researchers have made significant efforts to utilize inorganic-based semiconductors or their hybrid nanoarchitectures and have primarily undertaken research employing these materials (Hou, et al, 2011;Jheng, et al, 2020). Applications such as imaging, medical sensing, secure communication, and assessment of many surrounding surroundings are conceivable thanks to UV ray detection, and active research is underway (Zeng, et al, 2019).…”