Dual–Functional Ultra–Wide Bandgap AlGaN Material for Making Electrically Self–Protective Deep–Ultraviolet Optoelectronic Devices With Improved Frequency Responsivity

ABSTRACT

We propose a Al _0.65 Ga _0.35 N ultra‐widebandgap semiconductor‐based monolithic integrated optoelectronic device. The prototype optoelectronic device integrates a deep ultraviolet light‐emitting diode (DUV LED) and a Schottky barrier diode (SBD) on the same chip, which simultaneously achieves light emission and current rectification in alternating current (AC) operation conditions. The integrated device produces 279 nm electroluminescence when operated in the positive half‐cycle for the AC bias. The SBD operates in blocking mode when the device is in the negative half‐cycle for the AC bias. The breakdown voltage is −49 V, while the leakage current for the integrated device is 1.78 × 10 ⁻¹⁰ A/cm ² at the bias of −5 V. The leakage current is lower than 3.8 × 10 ⁻³  A/cm ² even at the bias of −30 V. Such an excellent blocking effect protects DUV LED from being damaged by the mistaken reverse bias. Therefore, the fabricated device achieves stable half‐wave rectification in AC bias conditions with a peak‐to‐peak voltage difference up to 60 V, such that under 20 000 cycles at the frequency of 50 Hz, the device demonstrates a highly stable current waveform. The reduced device capacitance generates an increased −3 dB modulation bandwidth ( f _−3 dB ) of ∼300 MHz, which poses the possibility of f _−3 dB > 800 MHz when the chip size further decreases.