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国家自然科学基金(10774001)

作品数:10 被引量:6H指数:2
相关作者:沈波桑立雯张国义秦志新李广如更多>>
相关机构:北京大学更多>>
发文基金:国家自然科学基金国家重点基础研究发展计划国家教育部博士点基金更多>>
相关领域:电子电信理学更多>>

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10 条 记 录,以下是 1-10
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氢化作用对低能电子束辐照下GaN发光演变的影响
2009年
结合氢在GaN中的扩散特性,运用阴极荧光(CL)谱,对氢化前后低能电子束辐照下GaN带边发光强度的演变进行了研究.实验发现,氢化前GaN在低能电子束辐照下带边发光强度呈现衰减的趋势,而氢化后带边发射强度先上升后衰减,而且氢化后的衰减比氢化前弱.1h辐照过程中,氢化后GaN带边发光强度的变化比氢化前要小很多.另外,实验中发现经过氢化处理的GaN在辐照后20h内没有观察到带边发射强度的恢复.研究表明氢原子在GaN中可以钝化缺陷来增强发光,但这种钝化缺陷的作用必须通过克服高的扩散势垒来实现,而低能电子束可以提供足够的能量使得氢原子克服扩散势垒来实现钝化作用.研究实验充分证明了氢的扩散是GaN中实现氢钝化作用的一个重要前提.
王彦沈波Dierre BenjaminSekiguchi Takashi许福军
关键词:氢化
Optimization of a solar-blind and middle infrared two-colour photodetector using GaN-based bulk material and quantum wells
2009年
This paper calculates the wavelengths of the interband transitions as a function of the Al mole fraction of AlxGa1-xN bulk materml. It is finds that when the Al mole fraction is between 0.456 and 0.639, the wavelengths correspond to the solar-blind (250 nm to 280 nm). The influence of the structure parameters of AlyGa1-yN/GaN quantum wells on the wavelength and absorption coefficient of intersubband transitions has been investigated by solving the SchrSdinger and Poisson equations self-consistently. The Al mole fraction of the AlyGa1-yN barrier changes from 0.30 to 0.46, meanwhile the w;dth of the well changes from 2.9 nm to 2.2 am, for maximal intersubband absorption in the window of the air (3μm 〈 A 〈 5μm). The absorption coefficient of the intersubband transition between the ground state and the first excited state decreases with the increase of the wavelength. The results are finally used to discuss the prospects of GaN-based bulk material and quantum wells for a solar-blind and middle infrared two-colour photodetector.
岑龙斌沈波秦志新张国义
Low resistance Ti/Al/Ni/Au Ohmic contact to (NH4)2Sx treated n-type GaN for high temperature applications
Low resistance Ti/Al/Ni/Au Ohmic contact to (NH4)2Sx treated n-type GaN has been studied in the temperature ra...
F.LinB.ShenS.HuangF.J.XuH.Y YangW.H.ChenN.MaZ.X.QinG.Y.Zhang
Influence of applied electric field on the absorption coefficient and subband distances in asymmetrical AlN/GaN coupled double quantum wells
2009年
The influence of applied electric fields on the absorption coefficient and subband distances in asymmetrical A1N/GaN coupled double quantum wells (CDQWs) has been investigated by solving SchrSdinger and Poisson equations self-consistently. It is found that the absorption coefficient of the intersubband transition (ISBT) between the ground state and the third excited state (lodd - 2even) can be equal to zero when the electric fields are applied in asymmetrical A1N/GaN CDQWs, which is related to applied electric fields induced symmetry recovery of these states. Meanwhile, the energy distances between 1odd - 2even and 1even - 2even subbands have different relationships from each other with the increase of applied electric fields due to the different polarization-induced potential drops between the left and the right wells. The results indicate that an electrical-optical modulator operated within the opto-communication wavelength range can be realized in spite of the strong polarization-induced electric fields in asymmetrical A1N/GaN CDQWs.
岑龙斌沈波秦志新张国义
GaN基p-i-n型雪崩探测器的制备与表征(英文)被引量:2
2011年
制备和表征了p-i-n型的GaN基雪崩探测器。器件在-5 V下的暗电流约为0.05 nA,-20 V下的暗电流小于0.5 nA。响应增益-偏压曲线显示,可重复的雪崩增益起始于80 V附近,在85 V左右增益达到最大为120,表明所制备的器件具有较好的质量。C-V测量用来确定载流子的分布和耗尽信息,结果显示,p型层在15 V左右达到耗尽,对应的空穴载流子浓度在1.9×1017 cm-1左右,相对低的载流子浓度降低了电场限制,使探测器的工作电压相对偏高。在不同偏压下测量的光谱响应曲线显示出明显的Franz-Keldysh效应。
李广如秦志新桑立雯沈波张国义
关键词:紫外探测器雪崩碰撞电离
Al_xGa_(1-x)N/GaN异质结构中2DEG的塞曼自旋分裂
通过在低温和强磁场下的磁输运测量研究了非故意掺杂Al_(0.24)Ga_(0.76)N/GaN异质结构中二维电子气(2DEG)的磁电阻振荡现象。在强磁场下观察到了表征2DEG塞曼自旋分裂的舒勃尼科夫-德哈斯(SdH)振荡...
唐宁沈波韩奎卢芳超许福军秦志新张国义
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In气氛下晶体生长对Mg掺杂p-AlxGa1-xN激活能的影响
2010年
Ⅲ-Ⅴ族氮化物宽禁带半导体材料体系中,普通方法生长的p型外延层电导率一般都很低,成为了制约器件性能提高的瓶颈。在p-AlxGa1-xN材料中,Mg受主的激活能较大,并且随Al组份增加而增大。通过在p-AlxGa1-xN材料生长过程中引入三甲基铟(TMIn),发现能有效地降低AlxGa1-xN材料中受主态的激活能。为研究不同In气氛下生长的p-AlxGa1-xN材料的性质,在使用相同二茂基镁(CP2Mg)的情况下,改变TMIn流量,生长了A,B,C和D四块样品。X射线衍射(XRD)组份分析表明:在1100℃下生长AlxGa1-xN外延层时,In的引入不会影响晶体组份。利用变温霍尔(Hall)测试研究了p-AlxGa1-xN材料中受主的激活能,结果表明:In气氛下生长的外延层相比无In气氛下生长的外延层,受主激活能明显降低,电导率显著提高。采用这种方法改进深紫外发光二极管(LED)的p-AlxGa1-xN层后,LED器件性能明显提高。
张延召秦志新桑立雯许正昱于涛杨子文沈波张国义赵岚张向锋成彩晶孙维国
关键词:激活能
Identification and elimination of inductively coupled plasma-induced defects in Al_xGa_(1-x)N/GaN heterostructures被引量:1
2011年
By using temperature-dependent Hall, variable-frequency capacitance-voltage and cathodoluminescence (CL) measurements, the identification of inductively coupled plasma (ICP)-induced defect states around the AlxGa1-xN/GaN heterointerface and their elimination by subsequent annealing in AlxGa1-xN/GaN heterostructures are systematically investigated. The energy levels of interface states with activation energies in a range from 0.211 to 0.253 eV below the conduction band of GaN are observed. The interface state density after the ICP-etching process is as high as 2.75× 10^12 cm^-2.eV^-1. The ICP-induced interface states could be reduced by two orders of magnitude by subsequent annealing in N2 ambient. The CL studies indicate that the ICP-induced defects should be Ga-vacancy related.
林芳沈波卢励吾刘新宇魏珂许福军王彦马楠黄俊
Structural characterization of V/Al/V/Au Ohmic contacts to n-type Al_(0.4)Ga_(0.6)N
2011年
This paper investigates the temperature dependence of the specific resistance in annealed V/Al/V/Au (15 nm/85 nm/20 nm/95 nm) contacts on n-A10.4Ga0.6N. Contacts annealed at 700 ℃ and higher temperatures show Ohmic behaviour. Annealing at 800 ℃ produces the lowest contact resistance. Samples annealed at 800 ℃have been analysed by using cross-sectional transmission electron microscopy and an energy dispersive x-ray spectrum. Limited reaction depths are observed between V-based contacts and n-AlGaN. The VN grains are found to form in the contact layer of the annealed samples, which can be considered as the key to the successful formation of Ohmic contact. The contact layer adjacent to AlGaN material consists of V Al-Au-N, AlN and AlAu alloys.
李涛秦志新许正昱沈波张国义
关键词:VANADIUM
Different temperature dependence of carrier transport properties between Al_xGa_(1-x)N/In_yGa_(1-y)N/GaN and Al_xGa_(1-x)N/GaN heterostructures被引量:3
2011年
The temperature dependence of carrier transport properties of Alx Gal-xN/InyGal-yN/CaN and AlzGal-xN/GaN heterostructures has been investigated. It is shown that the Hall mobility in Alo.25Gao.75N/Ino.03Gao.97N/GaN heterostructures is higher than that in Alo.25Gao.75N/GaN heterostructures at temperatures above 500 K, even the mobility in the former is much lower than that in the latter at 300 K. More importantly, the electron sheet density in Alo.25Gao.75N/Ino.03Gao.97N/GaN heterostructures decreases slightly, whereas the electron sheet density in Al0.25Gao.75N/CaN heterostructures gradually increases with increasing temperature above 500 K. It is believed that an electron depletion layer is formed due to the negative polarization charges at the Iny Can-yN/GaN heterointerface induced by the compressive strain in the InyCal-yN channel, which effectively suppresses the parallel conductivity originating from the thermal excitation in the underlying GaN layer at high temperatures.
宋杰许福军黄呈橙林芳王新强杨志坚沈波
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