This paper discusses the effect of N2 plasma treatment before dielectric deposition on the electrical performance of a Al203/AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor （MISHEMT）,with A...This paper discusses the effect of N2 plasma treatment before dielectric deposition on the electrical performance of a Al203/AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor （MISHEMT）,with Al203 deposited by atomic layer deposition.The results indicated that the gate leakage was decreased two orders of magnitude after the Al203/AlGaN interface was pretreated by N2 plasma.Furthermore,effects of N2 plasma pretreatrnent on the electrical properties of the AlGaN/Al2O3 interface were investigated by x-ray photoelectron spectroscopy measurements and the interface quality between Al203 and AlGaN film was improved.展开更多
AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors(MISHEMTs)with sodium beta-alumina(SBA)thin films as the gate dielectrics are studied.AlGaN/GaN metal-semiconductor high-electron-mobility tran...AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors(MISHEMTs)with sodium beta-alumina(SBA)thin films as the gate dielectrics are studied.AlGaN/GaN metal-semiconductor high-electron-mobility transistors(MESHEMTs)and MISHEMTs with Al_(2)O_(3) thin-film gate dielectrics are also fabricated for comparative study.The MISHEMTs with SBA gate dielectrics show nearly four orders of magnitude lower gate leakage current and an approximately 60%increase in maximum transconductance,indicating that SBA can serve as an effective dielectric for AlGaN/GaN MISHEMTs.However,SBA gate dielectrics result in threshold voltage modulation of AlGaN/GaN MISHEMTs.Compared with those of AlGaN/GaN MESHEMTs,the threshold voltages of AlGaN/GaN MISHEMTs with Al_(2)O_(3) gate dielectrics shift negatively from-5.5 V to-7.5 V.In contrast with the normally used gate dielectrics,the threshold voltages of MISHEMTs with SBA gate dielectrics shift positively from-5.5 V to-3.5 V.Based on an x-ray photoelectron spectrum study and energy band spectrum calculation,the primary mechanism of the threshold voltage modulation is attributed to the decrease in the surface valence-band maximum and the increase in the barrier height by SBA gate dielectrics.展开更多
An A1GaN/GaN metal-insulator-semiconductor high-electron-mobility transistor （MISHEMT）, with sodium beta-alumina （SBA） for both gate insulation and surface passivation, was investigated and compared with a convent...An A1GaN/GaN metal-insulator-semiconductor high-electron-mobility transistor （MISHEMT）, with sodium beta-alumina （SBA） for both gate insulation and surface passivation, was investigated and compared with a conventional metal-semiconductor high-electron-mobility transistor （MESHEMT）. The measured gate leakage current of the MISHEMT was reduced by approximately one order of magnitude as compared with that of the con- ventional MESHEMT. The saturation drain current of the A1GaN/GaN MISHEMT reached 830 mA/mm, which was about 43% higher than that of a conventional MESHEMT. The peak extrinsic transconductance of the MISHEMT was 103 mS/mm, which was similarly higher than that of the MESHEMT. The results suggested that the SBA thin film is an effective candidate gate dielectric for AIGaN/GaN MISHEMTs.展开更多
Sodium beta-alumina （SBA） is deposited on A1GaN/GaN by using a co-deposition process with sodium and Al2O3 as the precursors. The X-ray diffraction （XRD） spectrum reveals that the deposited thin film is amorphous....Sodium beta-alumina （SBA） is deposited on A1GaN/GaN by using a co-deposition process with sodium and Al2O3 as the precursors. The X-ray diffraction （XRD） spectrum reveals that the deposited thin film is amorphous. The binding energy and composition of the deposited thin film, obtained from the X-ray photoelectron spectroscopy （XPS） measurement, are consistent with those of SBA. The dielectric constant of the SBA thin film is about 50. Each of the capacitance voltage characteristics obtained at five different frequencies shows a high-quality interface between SBA and A1GaN. The interface trap density of metal-insulator-semiconductor high-electron-mobility transistor （MISHEMT） is measured to be （3.5-9.5）× 10^10 cm-2.eV-1 by the conductance method. The fixed charge density of SBA dielectric is on the order of 2.7× 1012 cm-2. Compared with the A1GaN/GaN metal-semiconductor heterostructure high-electron- mobility transistor （MESHEMT）, the A1GaN/GaN MISHEMT usually has a threshold voltage that shifts negatively. However, the threshold voltage of the A1GaN/GaN MISHEMT using SBA as the gate dielectric shifts positively from -5.5 V to -3.5 V. From XPS results, the surface valence-band maximum （VBM-EF） of A1GaN is found to decrease from 2.56 eV to 2.25 eV after the SBA thin film deposition. The possible reasons why the threshold voltage of A1GaN/GaN MISHEMT with the SBA gate dielectric shifts positively are the influence of SBA on surface valence-band maximum （VBM-EF）, the reduction of interface traps and the effects of sodium ions, and/or the fixed charges in SBA on the two-dimensional electron gas （2DEG）.展开更多
We report the studies of AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors(MISHEMTs) using reactive-sputtered La2O3 as the gate dielectric and the surface passivation layer.The device presents...We report the studies of AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors(MISHEMTs) using reactive-sputtered La2O3 as the gate dielectric and the surface passivation layer.The device presents a maximum drain current of 829 mA/mm and a maximum transconductance of 105 mS/mm,while the gate leakage current in the reverse direction is reduced by two orders of magnitude and the forward gate voltage swing increased to +5 V without gate breakdown.Compared to HEMT devices of similar geometry,MISHEMTs present a significant drain current recovery form current collapse.展开更多
基金Project supported by National Advanced Research Program (Grant No 51308030102)Xi’an Applied Materials Innovation Fund (Grant No XA-AM-200616)National Natural Science Foundation of China (Grant Nos 60506020 and 60676048)
文摘This paper discusses the effect of N2 plasma treatment before dielectric deposition on the electrical performance of a Al203/AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor （MISHEMT）,with Al203 deposited by atomic layer deposition.The results indicated that the gate leakage was decreased two orders of magnitude after the Al203/AlGaN interface was pretreated by N2 plasma.Furthermore,effects of N2 plasma pretreatrnent on the electrical properties of the AlGaN/Al2O3 interface were investigated by x-ray photoelectron spectroscopy measurements and the interface quality between Al203 and AlGaN film was improved.
基金Supported by the National Natural Science Foundation of China under Grant Nos 50932002 and 51172035.
文摘AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors(MISHEMTs)with sodium beta-alumina(SBA)thin films as the gate dielectrics are studied.AlGaN/GaN metal-semiconductor high-electron-mobility transistors(MESHEMTs)and MISHEMTs with Al_(2)O_(3) thin-film gate dielectrics are also fabricated for comparative study.The MISHEMTs with SBA gate dielectrics show nearly four orders of magnitude lower gate leakage current and an approximately 60%increase in maximum transconductance,indicating that SBA can serve as an effective dielectric for AlGaN/GaN MISHEMTs.However,SBA gate dielectrics result in threshold voltage modulation of AlGaN/GaN MISHEMTs.Compared with those of AlGaN/GaN MESHEMTs,the threshold voltages of AlGaN/GaN MISHEMTs with Al_(2)O_(3) gate dielectrics shift negatively from-5.5 V to-7.5 V.In contrast with the normally used gate dielectrics,the threshold voltages of MISHEMTs with SBA gate dielectrics shift positively from-5.5 V to-3.5 V.Based on an x-ray photoelectron spectrum study and energy band spectrum calculation,the primary mechanism of the threshold voltage modulation is attributed to the decrease in the surface valence-band maximum and the increase in the barrier height by SBA gate dielectrics.
基金supported by the National Natural Science Foundation of China(No.50932002)
文摘An A1GaN/GaN metal-insulator-semiconductor high-electron-mobility transistor （MISHEMT）, with sodium beta-alumina （SBA） for both gate insulation and surface passivation, was investigated and compared with a conventional metal-semiconductor high-electron-mobility transistor （MESHEMT）. The measured gate leakage current of the MISHEMT was reduced by approximately one order of magnitude as compared with that of the con- ventional MESHEMT. The saturation drain current of the A1GaN/GaN MISHEMT reached 830 mA/mm, which was about 43% higher than that of a conventional MESHEMT. The peak extrinsic transconductance of the MISHEMT was 103 mS/mm, which was similarly higher than that of the MESHEMT. The results suggested that the SBA thin film is an effective candidate gate dielectric for AIGaN/GaN MISHEMTs.
基金Project supported by the National Natural Science Foundation of China(Grant No.50932002)
文摘Sodium beta-alumina （SBA） is deposited on A1GaN/GaN by using a co-deposition process with sodium and Al2O3 as the precursors. The X-ray diffraction （XRD） spectrum reveals that the deposited thin film is amorphous. The binding energy and composition of the deposited thin film, obtained from the X-ray photoelectron spectroscopy （XPS） measurement, are consistent with those of SBA. The dielectric constant of the SBA thin film is about 50. Each of the capacitance voltage characteristics obtained at five different frequencies shows a high-quality interface between SBA and A1GaN. The interface trap density of metal-insulator-semiconductor high-electron-mobility transistor （MISHEMT） is measured to be （3.5-9.5）× 10^10 cm-2.eV-1 by the conductance method. The fixed charge density of SBA dielectric is on the order of 2.7× 1012 cm-2. Compared with the A1GaN/GaN metal-semiconductor heterostructure high-electron- mobility transistor （MESHEMT）, the A1GaN/GaN MISHEMT usually has a threshold voltage that shifts negatively. However, the threshold voltage of the A1GaN/GaN MISHEMT using SBA as the gate dielectric shifts positively from -5.5 V to -3.5 V. From XPS results, the surface valence-band maximum （VBM-EF） of A1GaN is found to decrease from 2.56 eV to 2.25 eV after the SBA thin film deposition. The possible reasons why the threshold voltage of A1GaN/GaN MISHEMT with the SBA gate dielectric shifts positively are the influence of SBA on surface valence-band maximum （VBM-EF）, the reduction of interface traps and the effects of sodium ions, and/or the fixed charges in SBA on the two-dimensional electron gas （2DEG）.
文摘We report the studies of AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors(MISHEMTs) using reactive-sputtered La2O3 as the gate dielectric and the surface passivation layer.The device presents a maximum drain current of 829 mA/mm and a maximum transconductance of 105 mS/mm,while the gate leakage current in the reverse direction is reduced by two orders of magnitude and the forward gate voltage swing increased to +5 V without gate breakdown.Compared to HEMT devices of similar geometry,MISHEMTs present a significant drain current recovery form current collapse.
