Metal–insulator–semiconductor(MOS) capacitor is a key structure for high performance MOS field transistors(MOSFETs), requiring low leakage current, high breakdown voltage, and low interface states. In this paper, β...Metal–insulator–semiconductor(MOS) capacitor is a key structure for high performance MOS field transistors(MOSFETs), requiring low leakage current, high breakdown voltage, and low interface states. In this paper, β-Ga_(2)O_(3) MOS capacitors were fabricated with ALD deposited Al_(2)O_(3) using H_(2)O or ozone(O_(3)) as precursors. Compared with the Al_(2)O_(3) gate dielectric with H_(2)O as ALD precursor, the leakage current for the O_(3) precursor case is decreased by two orders of magnitude, while it keeps the same level at the fixed charges, interface state density, and border traps. The SIMS tests show that Al_(2)O_(3) with O_(3) as precursor contains more carbon impurities. The current transport mechanism analysis suggests that the C–H complex in Al_(2)O_(3) with O_(3) precursor serves as deep energy trap to reduce the leakage current. These results indicate that the Al_(2)O_(3)/β-Ga_(2)O_(3)MOS capacitor using the O_(3) precursor has a low leakage current and holds potential for application in β-Ga_(2)O_(3) MOSFETs.展开更多
Doping modification is one of the most effective ways to optimize the thermoelectric properties of Bi_(2)Te_(3)-based alloys.P-type Bi_(2−x)Sb_(x)Te_(3) thermoelectric materials have been successfully prepared by dire...Doping modification is one of the most effective ways to optimize the thermoelectric properties of Bi_(2)Te_(3)-based alloys.P-type Bi_(2−x)Sb_(x)Te_(3) thermoelectric materials have been successfully prepared by direct Sb doping method.It can be found that doping Sb into Bi_(2)Te_(3) lattice array for Bi-site replacement facilitates the generation of Sb′Te anti-site defects.This anti-site defects can increase the hole concentration and optimize electrical transport properties of Bi_(2−x)Sb_(x)Te_(3) alloys.In addition,the point defects induced by mass and stress fluctuations and the Sb impurities produced during the sintering process can enhance the multi-scale phonon scattering and reduce the lattice thermal conductivity.As a result,the Bi_(0.47)Sb_(1.63)Te_(3) sample has a maximum thermoelectric figure of merit ZT of 1.04 at 350 K.It is worth noting that the bipolar effect of Bi_(2)Te_(3)-based alloys can be weakened with the increase of Sb content.The Bi_(0.44)Sb_(1.66)Te_(3) sample has a maximum average ZT value(0.93)in the temperature range of 300–500 K,indicating that direct doping of Sb can broaden the temperature range corresponding to the optimal ZT value.This work provides an idea for developing high-performance near room temperature thermoelectric materials with a wide temperature range.展开更多
基金Project supported in part by the Science and Technology Development Plan Project of Jilin Province, China (Grant No. YDZJ202303CGZH022)the National Key Research and Development Program of China (Grant No. 2024YFE0205300)+1 种基金the National Natural Science Foundation of China (Grant No. 62471504)the Open Fund of the State Key Laboratory of Optoelectronic Materials and Technologies (Sun Yat-Sen University) (Grant No. OEMT-2023KF-05)。
文摘Metal–insulator–semiconductor(MOS) capacitor is a key structure for high performance MOS field transistors(MOSFETs), requiring low leakage current, high breakdown voltage, and low interface states. In this paper, β-Ga_(2)O_(3) MOS capacitors were fabricated with ALD deposited Al_(2)O_(3) using H_(2)O or ozone(O_(3)) as precursors. Compared with the Al_(2)O_(3) gate dielectric with H_(2)O as ALD precursor, the leakage current for the O_(3) precursor case is decreased by two orders of magnitude, while it keeps the same level at the fixed charges, interface state density, and border traps. The SIMS tests show that Al_(2)O_(3) with O_(3) as precursor contains more carbon impurities. The current transport mechanism analysis suggests that the C–H complex in Al_(2)O_(3) with O_(3) precursor serves as deep energy trap to reduce the leakage current. These results indicate that the Al_(2)O_(3)/β-Ga_(2)O_(3)MOS capacitor using the O_(3) precursor has a low leakage current and holds potential for application in β-Ga_(2)O_(3) MOSFETs.
基金supported by the Anhui Province Natural Science Foundation for Excellent Youth Scholars(2208085Y17)the University Synergy Innovation Program of Anhui Province(GXXT-2022-008+1 种基金GXXT-2021-022)the Anhui Key Lab of Metal Material and Processing Open Project.
文摘Doping modification is one of the most effective ways to optimize the thermoelectric properties of Bi_(2)Te_(3)-based alloys.P-type Bi_(2−x)Sb_(x)Te_(3) thermoelectric materials have been successfully prepared by direct Sb doping method.It can be found that doping Sb into Bi_(2)Te_(3) lattice array for Bi-site replacement facilitates the generation of Sb′Te anti-site defects.This anti-site defects can increase the hole concentration and optimize electrical transport properties of Bi_(2−x)Sb_(x)Te_(3) alloys.In addition,the point defects induced by mass and stress fluctuations and the Sb impurities produced during the sintering process can enhance the multi-scale phonon scattering and reduce the lattice thermal conductivity.As a result,the Bi_(0.47)Sb_(1.63)Te_(3) sample has a maximum thermoelectric figure of merit ZT of 1.04 at 350 K.It is worth noting that the bipolar effect of Bi_(2)Te_(3)-based alloys can be weakened with the increase of Sb content.The Bi_(0.44)Sb_(1.66)Te_(3) sample has a maximum average ZT value(0.93)in the temperature range of 300–500 K,indicating that direct doping of Sb can broaden the temperature range corresponding to the optimal ZT value.This work provides an idea for developing high-performance near room temperature thermoelectric materials with a wide temperature range.
