Photoconductive Gain Behavior of Ni/β-Ga2O3 Schottky Barrier Diode-Based UV Detectors

TL;DR

Researchers developed a UV detector using a Ni/β-Ga2O3 diode that shows strong performance and internal gain.

Contribution

The study introduces a high-performance UV detector with internal gain and detailed photoresponse mechanisms in Ni/β-Ga2O3 Schottky diodes.

Findings

The device has a Schottky barrier height of 1.63 eV and a high rectification ratio of ~9.7 × 10^6.

It shows maximum responsivity at 255 nm and operates efficiently in self-powered mode under UV illumination.

The external quantum efficiency reaches 1.8 × 10^3% with rise and decay times under 60 ms.

Abstract

A vertical Ni/β-Ga2O3 Schottky barrier diode was fabricated on an unintentionally doped bulk (−201)-oriented β-Ga2O3 single crystal and investigated with a focus on the underlying photoresponse mechanisms. The device exhibits well-defined rectifying behavior, characterized by a Schottky barrier height of 1.63 eV, an ideality factor of 1.39, and a high rectification ratio of ~9.7 × 106 arb. un. at an applied bias of ±2 V. The structures demonstrate pronounced sensitivity to deep-ultraviolet radiation (λ ≤ 280 nm), with maximum responsivity observed at 255 nm, consistent with the wide bandgap of β-Ga2O3. Under 254 nm illumination at a power density of 620 μW/cm2, the device operates in a self-powered mode, generating an open-circuit voltage of 50 mV and a short-circuit current of 47 pA, confirming efficient separation of photogenerated carriers by the built-in electric field of the Schottky junction. The responsivity and detectivity of the structures increase from 0.18 to 3.87 A/W and from 9.8 × 108 to 4.3 × 1011 Hz0.5cmW−1, respectively, as the reverse bias rises from 0 to −45 V. The detectors exhibit high-speed performance, with rise and decay times not exceeding 29 ms and 59 ms, respectively, at an applied voltage of 10 V. The studied structures demonstrate internal gain, with the external quantum efficiency reaching 1.8 × 103%.

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