Capacitive β-Ga2O3 solar-blind photodetector with graphene electrode

Abstract

Conventional solar-blind photodetectors based on the conduction of photoexcited carriers are energy inefficient owing to the power dissipation caused by a resistive sensing mechanism and the narrow bandgap energy of the photon-absorbing layer. Herein, we demonstrate the energy-efficient capacitive sensing of deep-UV wavelengths by integrating an intrinsically solar-blind ultrawide bandgap (UWBG) β-Ga2O3 semiconductor with UV-transparent and conductive graphene electrode. A UWBG β-Ga2O3 eliminates the requirement of a solar-blind deep-UV bandpass filter. The high optical transmittance of the graphene enables UV-C light to be absorbed in the underlying β-Ga2O3, thereby facilitating carrier transport between the graphene electrode and β-Ga2O3. A capacitance change under UV-C excitation is observed, along with excellent reproductivity and spectral selectivity at various frequencies and bias conditions; the sensing performance improves with an increase in frequency. The average power dissipation of the fabricated photodetector in the stand-by (dark) and active (UV-C illumination) modes is 37.7 and 53.3 μW, respectively. Overall, this work introduces a new strategy for developing next-generation compact and energy-efficient solar-blind photodetectors.

Photo-enhanced metal-assisted chemical etching of α-gallium oxide grown by halide vapor-phase epitaxy on a sapphire substrate and its applications

“…The bi-exponential function is given by I ( t ) = I 0 + A e − t /τ 1 + B e − t /τ 2 .Here, I 0 is the dark current, A and B are constants, and τ 1 and τ 2 are time constants. 32 The time constants in the rise domain were τ r1 = 0.70 s and τ r2 = 1.97 s, and those in the decay domain were τ d1 = 0.03 s and τ d2 = 0.83 s. The rise/decay time constants of the UV-C MSM PD fabricated using PE-MAC etching were compared with the results reported in β-Ga 2 O 3 -based PD fabricated using conventional SF 6 -based plasma etching methods, which employed a capacitively induced plasma etcher operating at 150 W and 13.56 MHz. 33 The PE-MAC-etched PD recorded notably lower τ 1 and τ 2 , linked to intrinsic band-to-band transitions and slow reactions related to surface oxygen species or defects, respectively.…”