High-Responsivity Deep-Ultraviolet-Selective Photodetectors Using Ultrathin Gallium Oxide Films

Abstract

Wavelength-selective photodetectors responding to deep-ultraviolet (DUV) wavelengths (λ = 200–300 nm) are drawing significant interest in diverse sensing applications, ranging from micrometer biological molecules to massive military missiles. However, most DUV photodetectors developed thus far have suffered from long response times, low sensitivity, and high processing temperatures, impeding their practical use. Here, we report fast, high-responsivity, and general-substrate-compatible DUV photodetectors based on ultrathin (3–50 nm) amorphous gallium oxide (GaOX) films grown by low-temperature (∼<250 °C) atomic layer deposition (ALD) for the first time. ALD-grown GaOX films on glass substrates display a typical amorphous nature, which is identified by electron beam diffraction and X-ray diffraction measurements, while their band gap is sharply featured at ∼4.8 eV. Metal–semiconductor–metal photodetectors (active area of 30 × 30 μm2) using the 30-nm-thick GaOX films work reliably only for DUV wavelengths; t...