Al-Nanoparticle Sensitized <i>β</i>-Ga<sub>2</sub>O<sub>3</sub>-Based Solar-Blind Photodetector Fabricated via Focused Ion Beam Micro/Nano Processing
Shihao Fu, Yuefei Wang, Yurui Han, Enzhu Hou, Chong Gao, Bingsheng Li, Jiangang Ma, Zhendong Fu, Haiyang Xu, Aidong Shen, Yichun Liu
Abstract
The performance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3-based solar blind photodetector (PD) has been enhanced apparently by utilizing the effects of localized surface plasmon resonance of Al nanoparticles (Al NPs) array. The size and period of the Al NPs array are determined using the finite-difference time-domain method to obtain optimal resonance absorption with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3 in the solar-blind waveband. Al NPs were then fabricated using focused ion beam micro/nano processing on a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3-based metal-semiconductor-metal structure PD. The dark current of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3 structure with Al NPs ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3@Al) is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.72\times 10^{-{12}}\text{A}$ </tex-math></inline-formula> , which is two orders of magnitude lower than that of pure <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3 ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8.01\times 10^{-{10}}\text{A}$ </tex-math></inline-formula> ). This difference is attributed to the partial oxidation of the Al NPs, which forms Al2O3 and passivates the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3 interface. In addition, due to the resonance absorption and the hot electrons generated by the interband transition of the Al NPs, the light current increases threefold, resulting in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3@Al NP PD having a high light-to-dark current ratio of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.57\times 10^{{4}}$ </tex-math></inline-formula> . Under a bias of 20 V and 254-nm illumination ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$44.38\mu \text{W}$ </tex-math></inline-formula> /cm2), the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3@Al NP PD has high responsivity and detectivity of 131 A/W and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.17\times 10^{{14}}$ </tex-math></inline-formula> Jones, respectively. Furthermore, owing to the oxide shell Al2O3 passivation and the surface plasmons of the Al NPs, the persistent photoconductivity exhibited by the pure <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3 at rise time is suppressed and the decay time is sped up.