Modulated Al₂O₃-Alloyed Ga₂O₃ Materials and Deep Ultraviolet Photodetectors

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 (Ga₂O₃:Al₂O₃) absorption layers was deposited using radio frequency (RF) magnetron cosputter system with dual targets, in which the Ga₂O₃ target was sputtered with an RF power of 100 W and the Al₂O₃ target sputtered with various RF powers. The optical bandgap energy of the Ga₂O₃:Al₂O₃ films increased with an increase of the Al content deposited with a larger sputtered RF power of the Al₂O₃ target. In view of the suppression effect of the oxygen vacancy and the defect by the more Al-O bonds in the Ga₂O₃:Al₂O₃ 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 Ga₂O₃:Al₂O₃ 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 × 10¹¹ cmHz^0.5W^-1.Furthermore, the dominant low-frequency noise source was the flicker noise.