AlGaN ultraviolet Avalanche photodiodes based on a triple-mesa structure

Abstract

A high-performance Al0.1Ga0.9N ultraviolet (UV) avalanche photodiode (APD) with a separate absorption and multiplication structure grown on AlN templates is fabricated by employing a triple-mesa structure. The fabricated AlGaN UV-APD exhibits a maximum gain up to 2.3 × 104 at the reverse bias of 67 V and a low avalanche breakdown voltage (<70 V). The triple-mesa structure is confirmed to significantly lower the avalanche breakdown voltage and reduce the sidewall leakage current in comparison with the conventional double-mesa one. These improvements are explained by the simulation of the electric field which shows a significant improvement in the distribution uniformity in the active regions and enhancement in the intensity in the multiplication region. In addition, the scaling effects of various anodes and mesas are investigated, and the dark current is found to decrease with a decrease in the mesa size thanks to the reduced amount in the high-conductivity threading dislocation that crosses the multiplication region.

Progress on AlGaN-based solar-blind ultraviolet photodetectors and focal plane arrays

“…In addition to basic device structures, fabrication techniques can also be employed to improve device performance 210 . For example, bevel mesa and field plate terminal technologies can effectively homogenize the electric field distribution and are conducive to reducing the dark current and prevent the early breakdown of the device.…”

Performance Modulation for Back-Illuminated AlGaN Ultraviolet Avalanche Photodiodes Based on Multiplication Scaling

“…The Ti/Al/Ni/Au (30/150/50/100 nm) were deposited for ohmic contact on the n-Al 0.2 Ga 0.8 N layer and annealed at 800°C for 30 s in N 2 ambient, followed by the deposition of Ni/Au (20/20 nm) on p-GaN ohmic contact layer and annealed at 500°C for 10 min in air ambient. In addition, the APDs were carried out with a double-mesa processing by photolithography and ICP-RIE etching to suppress the leakage current and reduce the electrical field intensity on the sidewall of APDs, referring to our previous work [15], [16]. Finally, passivation layer of SiO 2 was deposited by PECVD and windows were opened for testing.…”

Deep-ultraviolet integrated photonic and optoelectronic devices: A prospect of the hybridization of group III–nitrides, III–oxides, and two-dimensional materials

“…sional Al x Ga 1−x N-based PDs in various applications [520] . Furthermore, group III-nitride-based avalanche photodetectors (APD), which show promise in providing higher photocurrent gains combined with high speeds and low operating voltages, are also of contemporary interest in the community [521][522][523][524][525][526][527][528][529] .…”