Temperature enhanced responsivity and speed in an AlGaN/GaN metal-heterostructure-metal photodetector

Abstract

An AlGaN/GaN metal-heterostructure-metal (MHM) ultraviolet (UV) photodetector employing lateral Schottky contacts was fabricated and characterized at different temperatures. As the temperature increased from 25 to 250 °C, the photoresponsivity of the MHM photodetector increased 3.5 times. This was attributed to the spontaneous-polarization-induced spatial separation of the photogenerated electrons and holes and the increased optical absorption at higher temperatures. Meanwhile, the decay time constant of the photocurrent became approximately three orders of magnitude smaller. With the enhanced photoresponsivity and the decreased response time constant, kilohertz optical switching of the MHM photodetector was recorded at 250 °C. The AlGaN/GaN MHM photodetector, sharing the same GaN-on-Si electronics platform, provides an applicable candidate for an all-GaN integrated UV sensing and amplifying system for high-temperature applications.

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

“…The output signals, as exhibited in Figure b–e, for 50 Hz, 100 Hz, 500 Hz, and 1 kHz, were captured at 293 K environment by an oscilloscope (Tektronix MDO34). The obvious elongated recovery time of the photocurrent is known as the persistent photoconductivity (PPC) effect, which is mostly attributed to the numerous defect-induced trap states in the device. , This universally observed PPC effect severely limits the response speed in GaN-based optoelectronic devices. − It has been reported that elevated temperatures can accelerate atom migration and therefore promote carrier collection to suppress the PPC effect. ,,, However, it brings drawbacks as an additional heating unit with extra power consumption is required. Fortunately, in this work, arising from the narrow fin width, the drift length of the photocarriers is shortened, and carriers can reach high velocity at a low bias voltage.…”

“…52−54 It has been reported that elevated temperatures can accelerate atom migration and therefore promote carrier collection to suppress the PPC effect. 15,20,55,56 However, it brings drawbacks as an additional heating unit with extra power consumption is required. Fortunately, in this work, arising from the narrow fin width, the drift length of the photocarriers is shortened, and carriers can reach high velocity at a low bias voltage.…”

“…However, these superior performances depend primarily on the bias voltage applied to these devices. The typical working bias of these AlGaN/GaN-based UV phototransistors and detectors is in a range from 5 to 15 V. ,− For some designs of phototransistors (except the floating p-GaN gated structures), ,, additional gate bias around 5 V is also required. ,,, Hypothetically, if these devices were to be biased below 500 mV, up to 60–99% performance degradation would manifest in their applications.…”

Vacuum Ultraviolet Photodetector with Low Dark Current and Fast Response Speed Based on Polycrystalline AlN Thin Film

“…The increase in photocurrent density with increasing the temperature should be associated with the enhanced absorption of AlN at elevated temperature, which in turn leads to the absorption of more photons emitted by the 185 nm lamp. [ 37–40 ] After turning off the light, the device can quickly recover the initial value in the dark state at all temperatures.…”

A Study on the Increase of Leakage Current in AlGaN Detectors with Increasing Al Composition

“…Since Al x Ga 1-x N ultraviolet (UV) detectors can play an important role in flame warning, biochemical detection, missile tracing, biomedical detection and other areas involving UV detection [ 1 , 2 , 3 ], there has been much research carried out on Al x Ga 1-x N UV photodetectors in recent years. Several studies have been carried out on various types of detectors, such as Schottky barrier [ 4 ], Metal–Semiconductor–Metal (MSM) [ 5 ] and p-i-n [ 6 ] structures. In addition, solar-blind focused plane arrays [ 7 ] have been realized.…”