Modulated Al₂O₃-Alloyed Ga₂O₃Materials and Deep Ultraviolet Photodetectors

Abstract

To modulate the cutoff wavelength of the metal-semiconductor-metal deep ultraviolet photodetectors (MSM DUV-PDs), the aluminum content of the aluminium oxide-alloyed gallium oxide (Ga ₂ O ₃ :Al ₂ O ₃ ) absorption layers was deposited using radio frequency (RF) magnetron cosputter system with dual targets, in which the Ga ₂ O ₃ target was sputtered with an RF power of 100 W and the Al ₂ O ₃ target sputtered with various RF powers. The optical bandgap energy of the Ga ₂ O ₃ :Al ₂ O ₃ films increased with an increase of the Al content deposited with a larger sputtered RF power of the Al ₂ O ₃ target. In view of the suppression effect of the oxygen vacancy and the defect by the more Al-O bonds in the Ga ₂ O ₃ :Al ₂ O ₃ absorption layer, the noise performances and the detectivity of the MSM DUV-PDs were improved. For depositing the Al atomic percentage of 5.9% in the Ga ₂ O ₃ :Al ₂ O ₃ absorption layer, the resulting MSM DUV-PDs revealed the cutoff wavelength of 230 nm, the noise equivalent power of 2.80 × 10 ^-12 W, and the detectivity of 1.37 × 10 ¹¹ cmHz0.5W ^-1 . Furthermore, the dominant low-frequency noise source was the flicker noise.