100 mV Ultra-Low Bias AlGaN/GaN Photodetector Based on Fin-Shaped Capacitor Configuration for Future Integrated Optoelectronics

Abstract

This study presents an AlGaN/GaN ultraviolet (UV) photodetector proven to be highly effective when working under an ultra-low bias voltage. The proposed photodetector is based on an innovative configuration consisting of repetitive AlGaN/GaN fin-shaped capacitor units, which make use of the two-dimensional electron gas (2DEG) layer as the positive field plates and the sidewall tungsten Schottky metal as the ground plates to surround the bulk of photocarrier generation space. Furthermore, a unique partial sidewall oxide structure is fabricated to partition the 2DEG field plates from the ground plates and to enable proper depletion field formation. With the special structure design, the symmetrical three-dimensional depletion fields are formed within each fin-shaped capacitor unit to spatially pinch off the entire bulk region at an ultra-low bias voltage. Effective photocarrier collection can then be achieved by such an extensive field coverage. When biased at 100 mV, intriguing performances in response to 365 nm UV were demonstrated by the fabricated prototype, such as a photocurrent-to-dark-current-ratio of 7.0 × 104, a peak responsivity of 1.1 × 103 A/W, as well as a large detectivity of 1.1 × 1016 Jones. Good transient performance was also observed under 365 nm UV pulses of 0.7 mW/cm2 in intensity with an operating frequency of up to 1 kHz. This work embodies an ultra-low voltage UV photodetector on the AlGaN/GaN epitaxy heterojunction platform with concise and complementary metal-oxide-semiconductor (CMOS)-compatible fabrication procedures, opening up an appealing potential in ultra-low-power optoelectronic integrated circuits for future Internet of Things and edge computing applications.

Ultrahigh-Responsivity Ultraviolet Photodetectors Based on AlGaN/GaN Double-Channel High-Electron-Mobility Transistors

“…The responsivity decreased with increasing wavelength of incident light and demonstrated a sharp cutoff at around 365 nm, which corresponds to the bandgap of the GaN layer . Based on the responsivity versus illumination wavelength curve, the UV/visible rejection ratio, which slightly decreased with increasing drain voltage, could be calculated as the maximum of about 2.5 × 10 3 at drain voltage of 0.1 V, which is better than the traditional GaN based Schottky, p-i-n, and metal–semiconductor-metal (MSM)-type PDs. − It should be noted that the responsivity of the device was still on the order of 10 4 at such an ultralow drain voltage, which could be comparable to the UV PDs based on AlGaN/GaN fin-shaped capacitor, and may largely reduce the power consumption.…”

High-Speed and Ultrasensitive Solar-Blind Ultraviolet Photodetectors Based on In Situ Grown β-Ga2O3 Single-Crystal Films

“…The monochromatic tunable light source was modulated by a chopper at frequency ranging from 200 to 800 Hz. The photocurrent responses were measured by the voltage on the resistor (200 kΩ) in series with the PDs. , The output signals at different frequencies were captured by an oscilloscope (DSOS054A, Keysight). Figure S5 (Supporting Information) shows the photoresponse of S 1 –S 4 at 200, 500, and 800 Hz, respectively.…”

Enhanced Performance of Ultraviolet AlGaN/GaN Photo‐HEMTs by Optimized Channel Isolation Schemes

“…Among various device structures, two-dimensional electron gas (2DEG) at the AlGaN/GaN HEMT has enabled a significant revolution in the development of the high-frequency power transistor [12] and highly responsive UV PDs. [13,14] Specifically, 2DEG AlGaN/GaN PDs outperform other types of GaN PDs based on p-i-n, [15] Schottky barrier, [16] avalanche, [17] field effect transistor, [18] fin-shaped capacitor, [19] and metal−semiconductor−metal (MSM) structure. [20,21] In addition, the fabrication process of AlGaN/GaN 2DEG PDs is well compatible with the matured GaN fabrication technology.…”