We report on an improved metal-graphene ohmic contact in bilayer epitaxial graphene on a SiC substrate with contact resistance below 0.1 Ω.mm. Monolayer and bilayer epitaxial graphenes are prepared on a 4HoSiC substr...We report on an improved metal-graphene ohmic contact in bilayer epitaxial graphene on a SiC substrate with contact resistance below 0.1 Ω.mm. Monolayer and bilayer epitaxial graphenes are prepared on a 4HoSiC substrate in this work. Their contact resistances are measured by a transfer length method. An improved photoresist-free device fabrication method is used and is compared with the conventional device fabrication method. Compared with the monolayer graphene, the contact resistance Rc of bilayer graphene improves from an average of 0.24Ω·mm to 0. 1 Ωmm. Ohmic contact formation mechanism analysis by Landauer's approach reveals that the obtained low ohmic contact resistance in bilayer epitaxial graphene is due to their high carrier density high carrier transmission probability, and p-type doping introduced by contact metal Au.展开更多
Spinel (O01)-orientated Mn304 thin films on Nb-doped SrTi03 (001) substrates are fabricated via the pulsed laser deposition method. X-ray diffraction and high-resolution transmission electron microscopy indicate t...Spinel (O01)-orientated Mn304 thin films on Nb-doped SrTi03 (001) substrates are fabricated via the pulsed laser deposition method. X-ray diffraction and high-resolution transmission electron microscopy indicate that the as-prepared epitaxial fihn is well crystaiHzed. In the film plane the orientation relationship between the film and the substrate is [lOOjMn3 04 ||[110] Nb-doped SrTiO3. After an electroforming process, the film shows bipolar nonvolatile resistance switching behavior. The positive voltage bias drives the sample into a low resistance state, while the negative voltage switches it back to a high resistance state. The switching polarity is different from the previous studies. The complex impedance measurement suggests that the resistance switching behavior is of filament type. Due to the performance reproducibility and state stability, Mn3O4 might be a promising candidate for the resistive random access memory devices.展开更多
In this study,the high performance of InGaN/GaN multiple quantum well light-emitting diodes(LEDs) with Aldoped ZnO(AZO) transparent conductive layers(TCLs) has been demonstrated.The AZO-TCLs were fabricated on t...In this study,the high performance of InGaN/GaN multiple quantum well light-emitting diodes(LEDs) with Aldoped ZnO(AZO) transparent conductive layers(TCLs) has been demonstrated.The AZO-TCLs were fabricated on the n-+-InGaN contact layer by metal organic chemical vapor deposition(MOCVD) using H2O as an oxidizer at temperatures as low as 400 ℃ without any post-deposition annealing.It shows a high transparency(98%),low resistivity(510 -4 Ω·cm),and an epitaxial-like excellent interface on p-GaN with an n+-InGaN contact layer.A forward voltage of 2.82 V @ 20 mA was obtained.Most importantly,the power efficiencies can be markedly improved by 53.8%@20 mA current injection and 39.6%@350 mA current injection compared with conventional LEDs with indium tin oxide TCL(LED-Ⅲ),and by28.8%@20 mA current injection and 4.92%@350 mA current injection compared with LEDs with AZO-TCL prepared by MOCVD using O2 as an oxidizer(LED-Ⅱ),respectively.The results indicate that the AZO-TCL grown by MOCVD using H2O as an oxidizer is a promising TCL for a low-cost and high-efficiency GaN-based LED application.展开更多
A novel structure of a VDMOS in reducing on-resistance is proposed. With this structure, the specific on-resistance value of the VDMOS is reduced by 22% of that of the traditional VDMOS structure as the breakdown volt...A novel structure of a VDMOS in reducing on-resistance is proposed. With this structure, the specific on-resistance value of the VDMOS is reduced by 22% of that of the traditional VDMOS structure as the breakdown voltage maintained the same value in theory, and there is only one additional mask in processing the new structure VDMOS, which is easily fabricated. With the TCAD tool, one 200 V N-channel VDMOS with the new structure is analyzed, and simulated results show that a specific on-resistance value will reduce by 23%, and the value by 33% will be realized when the device is fabricated in three epitaxies and four buried layers. The novel structure can be widely used in the strip-gate VDMOS area.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 61306006
文摘We report on an improved metal-graphene ohmic contact in bilayer epitaxial graphene on a SiC substrate with contact resistance below 0.1 Ω.mm. Monolayer and bilayer epitaxial graphenes are prepared on a 4HoSiC substrate in this work. Their contact resistances are measured by a transfer length method. An improved photoresist-free device fabrication method is used and is compared with the conventional device fabrication method. Compared with the monolayer graphene, the contact resistance Rc of bilayer graphene improves from an average of 0.24Ω·mm to 0. 1 Ωmm. Ohmic contact formation mechanism analysis by Landauer's approach reveals that the obtained low ohmic contact resistance in bilayer epitaxial graphene is due to their high carrier density high carrier transmission probability, and p-type doping introduced by contact metal Au.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CB921904 and 2012CB927402the National Natural Science Foundation of China under Grant Nos 11074142 and 11021464the Key Project of the Ministry of Education of China under Grant No 309003
文摘Spinel (O01)-orientated Mn304 thin films on Nb-doped SrTi03 (001) substrates are fabricated via the pulsed laser deposition method. X-ray diffraction and high-resolution transmission electron microscopy indicate that the as-prepared epitaxial fihn is well crystaiHzed. In the film plane the orientation relationship between the film and the substrate is [lOOjMn3 04 ||[110] Nb-doped SrTiO3. After an electroforming process, the film shows bipolar nonvolatile resistance switching behavior. The positive voltage bias drives the sample into a low resistance state, while the negative voltage switches it back to a high resistance state. The switching polarity is different from the previous studies. The complex impedance measurement suggests that the resistance switching behavior is of filament type. Due to the performance reproducibility and state stability, Mn3O4 might be a promising candidate for the resistive random access memory devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61204091,61404177,51402366,and U1201254)the Science and Technology Planning Project of Guangdong Province,China(Grant No.2015B010132006)
文摘In this study,the high performance of InGaN/GaN multiple quantum well light-emitting diodes(LEDs) with Aldoped ZnO(AZO) transparent conductive layers(TCLs) has been demonstrated.The AZO-TCLs were fabricated on the n-+-InGaN contact layer by metal organic chemical vapor deposition(MOCVD) using H2O as an oxidizer at temperatures as low as 400 ℃ without any post-deposition annealing.It shows a high transparency(98%),low resistivity(510 -4 Ω·cm),and an epitaxial-like excellent interface on p-GaN with an n+-InGaN contact layer.A forward voltage of 2.82 V @ 20 mA was obtained.Most importantly,the power efficiencies can be markedly improved by 53.8%@20 mA current injection and 39.6%@350 mA current injection compared with conventional LEDs with indium tin oxide TCL(LED-Ⅲ),and by28.8%@20 mA current injection and 4.92%@350 mA current injection compared with LEDs with AZO-TCL prepared by MOCVD using O2 as an oxidizer(LED-Ⅱ),respectively.The results indicate that the AZO-TCL grown by MOCVD using H2O as an oxidizer is a promising TCL for a low-cost and high-efficiency GaN-based LED application.
文摘A novel structure of a VDMOS in reducing on-resistance is proposed. With this structure, the specific on-resistance value of the VDMOS is reduced by 22% of that of the traditional VDMOS structure as the breakdown voltage maintained the same value in theory, and there is only one additional mask in processing the new structure VDMOS, which is easily fabricated. With the TCAD tool, one 200 V N-channel VDMOS with the new structure is analyzed, and simulated results show that a specific on-resistance value will reduce by 23%, and the value by 33% will be realized when the device is fabricated in three epitaxies and four buried layers. The novel structure can be widely used in the strip-gate VDMOS area.