High Quality <i>P</i>-Type Mg-Doped β-Ga<sub>2</sub>O<sub>3–δ</sub> Films for Solar-Blind Photodetectors
Xin Zhou, Ming Li, Jinzhong Zhang, Liyan Shang, Kai Jiang, Yawei Li, Liangqing Zhu, Zhigao Hu, Junhao Chu
Abstract
The ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\overline {{2}} {01}$ </tex-math></inline-formula> )-oriented Mg-doped <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\beta }$ </tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text {Ga}}_{2}{\text {O}}_{3- \delta }$ </tex-math></inline-formula> films were grown on (0001)-sapphire substrates by pulsed laser deposition (PLD) at various oxygen partial pressures ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{P}_{\text {O}}\,\,=10$ </tex-math></inline-formula> -40mTorr). The conductivity type of the as-deposited Mg-doped <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> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text {Ga}}_{2}{\text {O}}_{3- \delta }$ </tex-math></inline-formula> films is proved to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}$ </tex-math></inline-formula> -type according to the transfer characteristic curves of a top-gate field effect transistor (FET) and rectification curves of the Mg-doped /undoped <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> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text {Ga}}_{2}{\text {O}}_{3- \delta }$ </tex-math></inline-formula> junction. In addition, the two-terminal solar-blind photodetectors based on Mg-doped <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> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text {Ga}}_{2}{\text {O}}_{3- \delta }$ </tex-math></inline-formula> films prepared at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{P}_{\text {O}} =30$ </tex-math></inline-formula> mTorr exhibite a good optoelectrical performance with a low dark current of 0.19 pA at 10 V, a high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{I}_{\text {254nm}}/\text{I}_{\text {dark}}$ </tex-math></inline-formula> 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">${1.3}\,\,\times \,\,{10}^{{4}}$ </tex-math></inline-formula> , fast rise ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\tau }_{\text {r1}} =0.035\text{s}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\tau }_{\text {r2}} =0.241\text{s}$ </tex-math></inline-formula> ) and decay ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\tau }_{\text {d1}} =0.022\text{s}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\tau }_{\text {d2}} =0.238\text{s}$ </tex-math></inline-formula> ) times. The present work indicates that the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}$ </tex-math></inline-formula> -type Mg-doped <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> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text {Ga}}_{2}{\text {O}}_{3- \delta }$ </tex-math></inline-formula> films can be used in the third-generation ultraviolet photodetectors.