Two-terminal terahertz detectors based on AlGaN/GaN high-electron-mobility transistors

We report an approach to make two-terminal antenna-coupled AlGaN/GaN high-electron-mobility-transistor self-mixing terahertz detectors. Fluorine ion implantation is used to increase the threshold voltage of the AlGaN/GaN two-dimensional electron gas. An optimal implantation dose can be reached so that the detector responsivity is maximized at zero gate voltage or with the gate floating. The relationship between the ion dosage and the threshold voltage, electron mobility, electron density, responsivity, and noise-equivalent power (NEP) is obtained. A minimum optical NEP of 47 p W / Hz is achieved from a two-terminal detector at 0.65 THz. The capability of two-terminal operation allows for the design of a large array of antenna-coupled high-electron-mobility transistor detectors without the demanding needs of routing negative gate voltage lines around the antenna array and minimizing the gate leakage current.