Nonpolar(11–20) a-plane p-type GaN films were successfully grown on r-plane sapphire substrate with the metal–organic chemical vapor deposition(MOCVD) system. The effects of Mg-doping temperature on the structural a...Nonpolar(11–20) a-plane p-type GaN films were successfully grown on r-plane sapphire substrate with the metal–organic chemical vapor deposition(MOCVD) system. The effects of Mg-doping temperature on the structural and electrical properties of nonpolar p-type GaN films were investigated in detail. It is found that all the surface morphology, crystalline quality, strains, and electrical properties of nonpolar a-plane p-type GaN films are interconnected, and are closely related to the Mg-doping temperature. This means that a proper performance of nonpolar p-type GaN can be expected by optimizing the Mg-doping temperature. In fact, a hole concentration of 1.3×10^(18)cm^(-3), a high Mg activation efficiency of 6.5%,an activation energy of 114 me V for Mg acceptor, and a low anisotropy of 8.3% in crystalline quality were achieved with a growth temperature of 990℃. This approach to optimizing the Mg-doping temperature of the nonpolar a-plane p-type GaN film provides an effective way to fabricate high-efficiency optoelectronic devices in the future.展开更多
This work investigates the suppression and compensation effect of oxygen on the behaviors and characteristics of heavily boron-doped microwave plasma chemical vapor deposition(MPCVD)diamond films.The suppression effec...This work investigates the suppression and compensation effect of oxygen on the behaviors and characteristics of heavily boron-doped microwave plasma chemical vapor deposition(MPCVD)diamond films.The suppression effect of oxygen on boron incorporation is observed by an improvement in crystal quality when oxygen is added during the diamond doping process.A relatively low hole concentration is expected and verified by Hall effect measurements due to the compensation effect of oxygen as a deep donor in diamond.A low acceptor concentration,high compensation donor concentration and relatively larger acceptor ionization energy are then induced by the incorporation of oxygen;however,a heavily boron-doped diamond film with high crystal quality can also be expected.The formation of an oxygen–boron complex structure instead of oxygen substitution,as indicated by the results of x-ray photoelectron spectroscopy,is suggested to be more responsible for the observed enhanced compensation effect due to its predicted low formation energy.Meanwhile,density functional theory calculations show that the boron–oxygen complex structure is easily formed in diamond with a formation energy of-0.83 eV.This work provides a comprehensive understanding of oxygen compensation in heavily boron-doped diamond.展开更多
We report a universal method to transfer freestanding La_(0.7)Sr_(0.3)MnO_(3)membranes to target substrates.The 4-unit-cell-thick freestanding La_(0.7)Sr_(0.3)MnO_(3)membrane exhibits the enhanced ferromagnetism,condu...We report a universal method to transfer freestanding La_(0.7)Sr_(0.3)MnO_(3)membranes to target substrates.The 4-unit-cell-thick freestanding La_(0.7)Sr_(0.3)MnO_(3)membrane exhibits the enhanced ferromagnetism,conductivity and out-of-plane magnetic anisotropy,which otherwise shows nonmagnetic/antiferromagnetic and insulating behavior due to the intrinsic epitaxial strain.This work facilitates the promising applications of ultrathin freestanding correlated oxide membranes in electronics and spintronics.展开更多
Regulation with nitrogen and oxygen co-doping on growth and properties of boron doped diamond films is studied by using laughing gas as dopant. As the concentration of laughing gas(N2O/C) increases from 0 to 10%, the ...Regulation with nitrogen and oxygen co-doping on growth and properties of boron doped diamond films is studied by using laughing gas as dopant. As the concentration of laughing gas(N2O/C) increases from 0 to 10%, the growth rate of diamond film decreases gradually, and the nitrogen-vacancy(NV) center luminescence intensity increases first and then weakens. The results show that oxygen in laughing gas has a strong inhibitory effect on formation of NV centers, and the inhibitory effect would be stronger as the concentration of laughing gas increases. As a result, the film growth rate and nitrogen-related compensation donor decrease, beneficial to increase the acceptor concentration(~3.2×10^(19)cm^(-3)) in the film. Moreover, it is found that the optimal regulation with the quality and electrical properties of boron doped diamond films could be realized by adding appropriate laughing gas, especially the hole mobility(~700cm^(2)/V·s), which is beneficial to the realization of high-quality boron doped diamond films and high-level optoelectronic device applications in the future.展开更多
基金Project supported by the National Key Research and Development Program of China (Grant Nos.2021YFB3601000 and 2021YFB3601002)the National Natural Science Foundation of China (Grant Nos.62074077,61921005,61974062,62204121,and 61904082)+1 种基金Leading-edge Technology Program of Jiangsu Natural Science Foundation (Grant No.BE2021008-2)the China Postdoctoral Science Foundation (Grant No.2020M671441)。
文摘Nonpolar(11–20) a-plane p-type GaN films were successfully grown on r-plane sapphire substrate with the metal–organic chemical vapor deposition(MOCVD) system. The effects of Mg-doping temperature on the structural and electrical properties of nonpolar p-type GaN films were investigated in detail. It is found that all the surface morphology, crystalline quality, strains, and electrical properties of nonpolar a-plane p-type GaN films are interconnected, and are closely related to the Mg-doping temperature. This means that a proper performance of nonpolar p-type GaN can be expected by optimizing the Mg-doping temperature. In fact, a hole concentration of 1.3×10^(18)cm^(-3), a high Mg activation efficiency of 6.5%,an activation energy of 114 me V for Mg acceptor, and a low anisotropy of 8.3% in crystalline quality were achieved with a growth temperature of 990℃. This approach to optimizing the Mg-doping temperature of the nonpolar a-plane p-type GaN film provides an effective way to fabricate high-efficiency optoelectronic devices in the future.
基金supported by the National Key R&D Program of China(2022YFB3605400)the State Key Research and Development Project of Guangdong(2020B010174002)the National Natural Science Foundation of China(62234007,U21A20503 and U21A2071).
基金the National Key Research and Development Program of China(Grant Nos.2018YFB0406502,2017YFF0210800,and 2017YFB0403003)the National Natural Science Foundation of China(Grant Nos.61774081,61775203,61574075,61974059,61674077,61774081,and 91850112)+2 种基金the State Key Research and Development Project of Jiangsu,China(Grant No.BE2018115)State Key Laboratory of Wide-Bandgap Semiconductor Power Electric Devices(Grant No.2017KF001)Anhui University Natural Science Research Project(Grant No.KJ2021A0037).
文摘This work investigates the suppression and compensation effect of oxygen on the behaviors and characteristics of heavily boron-doped microwave plasma chemical vapor deposition(MPCVD)diamond films.The suppression effect of oxygen on boron incorporation is observed by an improvement in crystal quality when oxygen is added during the diamond doping process.A relatively low hole concentration is expected and verified by Hall effect measurements due to the compensation effect of oxygen as a deep donor in diamond.A low acceptor concentration,high compensation donor concentration and relatively larger acceptor ionization energy are then induced by the incorporation of oxygen;however,a heavily boron-doped diamond film with high crystal quality can also be expected.The formation of an oxygen–boron complex structure instead of oxygen substitution,as indicated by the results of x-ray photoelectron spectroscopy,is suggested to be more responsible for the observed enhanced compensation effect due to its predicted low formation energy.Meanwhile,density functional theory calculations show that the boron–oxygen complex structure is easily formed in diamond with a formation energy of-0.83 eV.This work provides a comprehensive understanding of oxygen compensation in heavily boron-doped diamond.
基金supported in part by the National Key R&D Program of China(Grant No.2022YFA1402404)the National Natural Science Foundation of China(Grant Nos.62274085,11874203,and 61822403)。
文摘We report a universal method to transfer freestanding La_(0.7)Sr_(0.3)MnO_(3)membranes to target substrates.The 4-unit-cell-thick freestanding La_(0.7)Sr_(0.3)MnO_(3)membrane exhibits the enhanced ferromagnetism,conductivity and out-of-plane magnetic anisotropy,which otherwise shows nonmagnetic/antiferromagnetic and insulating behavior due to the intrinsic epitaxial strain.This work facilitates the promising applications of ultrathin freestanding correlated oxide membranes in electronics and spintronics.
基金Project supported by the National Key R&D Program of China (Grant Nos. 2018YFB0406502, 2017YFF0210800, and 2017YFB0403003)the National Natural Science Foundation of China (Grant Nos. 61974059, 61674077, and 61774081)+1 种基金the Natural Science Foundation of Jiangsu Province (Grant No. BK20160065)the Fundamental Research Funds for the Central Universities。
文摘Regulation with nitrogen and oxygen co-doping on growth and properties of boron doped diamond films is studied by using laughing gas as dopant. As the concentration of laughing gas(N2O/C) increases from 0 to 10%, the growth rate of diamond film decreases gradually, and the nitrogen-vacancy(NV) center luminescence intensity increases first and then weakens. The results show that oxygen in laughing gas has a strong inhibitory effect on formation of NV centers, and the inhibitory effect would be stronger as the concentration of laughing gas increases. As a result, the film growth rate and nitrogen-related compensation donor decrease, beneficial to increase the acceptor concentration(~3.2×10^(19)cm^(-3)) in the film. Moreover, it is found that the optimal regulation with the quality and electrical properties of boron doped diamond films could be realized by adding appropriate laughing gas, especially the hole mobility(~700cm^(2)/V·s), which is beneficial to the realization of high-quality boron doped diamond films and high-level optoelectronic device applications in the future.
