Solar blind photodetector based on epitaxial zinc doped Ga₂O₃ thin film

Abstract

We report on the fabrication and characterization of solar blind photodetectors (SBPs) based on undoped β‐Ga2O3 and Zn doped (∼5 × 1020 cm−3) β‐Ga2O3 (ZnGaO) epitaxial films with cutoff wavelength of ∼260 nm. The epilayers were grown on c‐sapphire by the metal organic chemical vapor deposition technique and their structural, electrical and optical properties were characterized using various methods. As grown films have a large number of defects, resulting in detectors with enhanced internal gain, hence, high spectral responsivity >103 A/W. Post growth annealing in oxygen improved the quality of the epilayers, leading to detectors with reduced dark current (∼nA to ∼pA) and increased out of band rejection ratio. At 20 V bias, a ZnGaO detector showed a peak responsivity of 210 A/W (at 232 nm) and an out of band rejection ratio (i.e., R232 nm/R320 nm) of 5 × 104. Alternatively, for a β‐Ga2O3 detector these parameters were found to be five times and three times lower, respectively, suggesting that ZnGaO detectors have superior performance characteristics. These results provide a roadmap toward achieving high responsivity SBPs based on epitaxial ZnGaO films, laying a solid foundation for future applications.

Deep-Ultraviolet Photodetectors Based on Epitaxial ZnGa2O4 Thin Films

“…It was worthy to mention that the responsivity for the annealed ZnGa 2 O 4 PDs devices dropped significantly (Fig. 5(c)), which is consistent to those reported in earlier studies 12,22 . Even though, the selectivity of the DUV PDs made of ZnGa 2 O 4 annealed at 800 °C presents the highest for these DUV PDs.…”

“…The calculated carrier concentration, mobility, and resistivity of the ZnGa 2 O 4 films were 6.72 × 10 16  cm −3 , 1.4 cm 2 /Vs, and 67.9 Ω-cm, respectively. These values indicate that ZnGa 2 O 4 films are promising for several optoelectronic applications 12 . In this work, the solar-blind PDs made of the ZnGa 2 O 4 epilayers grown by MOCVD were studied.…”

Structural and Luminescence Properties of Ga2O3:Zn Micro‐ and Nanostructures

“…Due to this, the 2.6 eV band was considered a signature emission of the acceptor levels. Furthermore, Alema et al have also shown very recently that a band centered at 2.7 eV, is strongly influenced by the presence of Zn and specifically assigned it to recombination between V O donors and Zn Ga acceptors. Besides, a similar band around 480 nm (2.6 eV) was observed in Mn‐doped Ga 2 O 3 and tentatively assigned to levels related to the presence of Mn, which is usually in the Mn 2+ ionization state and would therefore result in p‐type doping .…”

Effect of Growth Pressure on PLD‐Deposited Gallium Oxide Thin Films for Deep‐UV Photodetectors

“…Gallium oxide has been shown to be a promising candidate for a wide variety of devices, including field‐effect transistors (FETs), Schottky barrier diodes, and UV photodetectors . The monoclinic form (β‐gallium oxide [β‐Ga 2 O 3 ]) of gallium oxide has been subjected to intensive research interests recently because of its thermal and chemical stabilities .…”