Vertical Solar-Blind Deep-Ultraviolet Schottky Photodetectors Based on β-Ga₂O₃Substrates

Abstract

A vertical-type Schottky photodetector based on a (100)-oriented β-Ga2O3 substrate has been fabricated with simple processes of thermal annealing and vacuum evaporation. The photodetector exhibited a rectification ratio higher than 106 at ±3 V, and showed deep-ultraviolet-light detection at reverse bias. The spectral response showed solar-blind sensitivity with high photoresponsivities of 2.6–8.7 A/W at wavelengths of 200–260 nm. These values were 35–150 times higher than those derived assuming the internal quantum efficiency to be unity. This fact is attributed to the carrier multiplication occurring in the highly resistive surface region that is subject to a high internal electric field of about 1.0 MV/cm at the reverse bias of 10 V.

Heteroepitaxial growth of ε-Ga2O3 thin films on cubic (111) MgO and (111) yttria-stablized zirconia substrates by mist chemical vapor deposition

“…In particular, Ga 2 O 3 exhibits a large bandgap (approximately 5 eV), 8) and its electrical conductivity can be controlled by introducing impurities into its matrix. 9) These properties have paved the way for new applications of this material, such as in the Schottky barrier diode 10) and MOSFET, 11) for next-generation power devices with a higher breakdown voltage than conventional GaN and SiC power devices, solar-blind photodetectors, 12) and flame detectors. 13) Ga 2 O 3 appears in five polymorphs, i.e., α-, β-, γ-, δ-, and ε-phases.…”

Electronic properties of the residual donor in unintentionally doped β-Ga2O3

“…[1][2][3] Its material properties are especially suited for high-voltage and high-power device applications and then even expected to be better than SiC and GaN. 4 The availability of native low-cost substrates is also an advantage of β-Ga2O3 over other wide bandgap semiconductors.…”

High responsivity in molecular beam epitaxy grown β-Ga2O3 metal semiconductor metal solar blind deep-UV photodetector

“…2 β-Ga 2 O 3 is an emerging wide band gap material (E G ~4.6 eV) which is at the focus of a rapidly-expanding device and materials community for its promise towards enabling nextgeneration high-power transistors [1][2][3] and deep UV solar blind detectors [4][5][6][7][8][9][10][11] towards strategic applications such as missile plume detection and bio-medical sensors. III-nitride alloys (AlGaN), which have been widely explored [12][13][14][15][16] for solar blind UV detection, suffer from lack of native substrates which is a major bottleneck to achieving superior material quality.…”

“…Both the photo and the dark current decreased slightly after the passivation of the devices. 5 With an incident power of ~ 0.7 mW/cm 2 over a device active area of ~ 300 µm x 360 µm, the maximum photo current is estimated to be ~ 0.15 µA (Assuming the external quantum efficiency to be 100 %) whereas the measured photo current using sourcemeter is ~ 4.6 µA ( at 20 V). This is a clear indication of the gain in the devices.…”

“…6 Fig . 5 illustrates the plot of the responsivity versus dark current for the state-of-the-art solar blind (230-290 nm) UV detectors reported [4][5][6]8,[10][11]16,[30][31][32][33][34][35][36][37] for the devices based on Al x Ga 1-x N as well as on β-Ga 2 O 3 . The detectors reported in this work have excellent responsivity while maintaining a very low dark current for 230-240 nm range.…”