Flame Detection by a β-Ga2O3-Based Sensor

An oxide semiconductor of beta-Ga2O3 has a natural solar-blind sensitivity due to its large bandgap of 4.8 eV. To evaluate its potential, a flame detector was fabricated using its conductive single crystal substrate applying a simple method without epitaxy and vacuum processes. The structure is a poly(3,4-ethylene dioxythiophene) complex with polystyrene sulfonic acid (PEDOT-PSS) Schottky contact/a semi-insulating layer of beta-Ga2O3/n-type region of beta-Ga2O3/an In ohmic contact. The spectral response of the detector exhibited a large 250-to-300-nm rejection ratio of 1.5 x 10(4) and an external quantum efficiency of 18% at 250 nm. The device successfully detected a flame by distinguishing 1.5nW/cm(2) solar-blind light from the flame under a strong fluorescent lamp illumination without any visible-cut filters. This result encourages the fabrication of practical beta-Ga2O3-based flame detectors. (c) 2009 The Japan Society of Applied Physics