InP-based high electron mobility transistors(HEMTs) will be affected by protons from different directions in space radiation applications. The proton irradiation effects on InAlAs/InGaAs hetero-junction structures o...InP-based high electron mobility transistors(HEMTs) will be affected by protons from different directions in space radiation applications. The proton irradiation effects on InAlAs/InGaAs hetero-junction structures of InP-based HEMTs are studied at incident angles ranging from 0 to 89.9° by SRIM software. With the increase of proton incident angle, the change trend of induced vacancy defects in the InAlAs/InGaAs hetero-junction region is consistent with the vacancy energy loss trend of incident protons. Namely, they both have shown an initial increase, followed by a decrease after incident angle has reached 30°. Besides, the average range and ultimate stopping positions of incident protons shift gradually from buffer layer to hetero-junction region, and then go up to gate metal. Finally, the electrical characteristics of InP-based HEMTs are investigated after proton irradiation at different incident angles by Sentaurus-TCAD. The induced vacancy defects are considered self-consistently through solving Poisson's and current continuity equations. Consequently, the extrinsic transconductance, pinch-off voltage and channel current demonstrate the most serious degradation at the incident angle of 30?, which can be accounted for the most severe carrier sheet density reduction under this condition.展开更多
The aim of this study was to design a cage-like radiotherapy system(CRTS)to further promote the clinical application of noncoplanar radiotherapy.The CRTS comprises two stands,two O-rings,several arc girders,an X-ray h...The aim of this study was to design a cage-like radiotherapy system(CRTS)to further promote the clinical application of noncoplanar radiotherapy.The CRTS comprises two stands,two O-rings,several arc girders,an X-ray head,an imaging subsystem,and a treatment couch.The X-ray head rotates with O-rings around the patient’s body and slides along the arc girder.Compared with the C-arm linear accelerator(C-Linac),the clinically available spatial irradiation angle ranges(SIARs)of the CRTS for the head,chest,and abdomen were 33%,63.6%,and 62.6%larger,respectively.Moreover,according to a preliminary planning comparison based on the dose distribution simulation method,the CRTS achieved much better protection of normal tissue than the C-Linac.Furthermore,the CRTS enabled accurate noncoplanar irradiation without movement of the body being irradiated,allowed automatic control of the movements of different parts without risk of collisions,and provided continuous radiation over an angle that considerably exceeded a full turn.These advantages make CRTS very promising for noncoplanar radiotherapy.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11775191,61404115,61434006,and 11475256)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province,China(Grant No.18IRTSTHN016)the Development Fund for Outstanding Young Teachers in Zhengzhou University of China(Grant No.1521317004)
文摘InP-based high electron mobility transistors(HEMTs) will be affected by protons from different directions in space radiation applications. The proton irradiation effects on InAlAs/InGaAs hetero-junction structures of InP-based HEMTs are studied at incident angles ranging from 0 to 89.9° by SRIM software. With the increase of proton incident angle, the change trend of induced vacancy defects in the InAlAs/InGaAs hetero-junction region is consistent with the vacancy energy loss trend of incident protons. Namely, they both have shown an initial increase, followed by a decrease after incident angle has reached 30°. Besides, the average range and ultimate stopping positions of incident protons shift gradually from buffer layer to hetero-junction region, and then go up to gate metal. Finally, the electrical characteristics of InP-based HEMTs are investigated after proton irradiation at different incident angles by Sentaurus-TCAD. The induced vacancy defects are considered self-consistently through solving Poisson's and current continuity equations. Consequently, the extrinsic transconductance, pinch-off voltage and channel current demonstrate the most serious degradation at the incident angle of 30?, which can be accounted for the most severe carrier sheet density reduction under this condition.
基金the National Natural Science Foundation of China(No.11475261)partially supported by the National Key Project of Research and Development of China(No.2016YFC0904600).
文摘The aim of this study was to design a cage-like radiotherapy system(CRTS)to further promote the clinical application of noncoplanar radiotherapy.The CRTS comprises two stands,two O-rings,several arc girders,an X-ray head,an imaging subsystem,and a treatment couch.The X-ray head rotates with O-rings around the patient’s body and slides along the arc girder.Compared with the C-arm linear accelerator(C-Linac),the clinically available spatial irradiation angle ranges(SIARs)of the CRTS for the head,chest,and abdomen were 33%,63.6%,and 62.6%larger,respectively.Moreover,according to a preliminary planning comparison based on the dose distribution simulation method,the CRTS achieved much better protection of normal tissue than the C-Linac.Furthermore,the CRTS enabled accurate noncoplanar irradiation without movement of the body being irradiated,allowed automatic control of the movements of different parts without risk of collisions,and provided continuous radiation over an angle that considerably exceeded a full turn.These advantages make CRTS very promising for noncoplanar radiotherapy.