分子束外延生长AlGaAs/GaAs GRINSCH SQW激光器中高温陷阱的研究

应用深能级瞬态谱(DLTS)技术研究分子束外延(MBE)生长的AlGaAs/GaAs gradedindex separate confinement heterostructure single well(GRIN-SCH SQW)激光器的高温陷阱。样品的DLTS表明,在激光器的n-AlGaAs层里存在着高温(空穴、电子)陷阱,它直接影响着激光器的性能。高温空穴陷阱可能分布在x_(Al)=0.2→0.43和x_(Al)=0.43的n-AlGaAs层界面附近,而高温电子陷阱则可能分布在X_(Al)=0.43的n-AlGaAs层里X_(Al)值不连续的界面附近。高温电子陷阱的产生可能与AlGaAs层里的O有关。     

MBE和MOCVD生长的AIGaAs/GaAs GRIN—SCH SQW激光器深中心的比较

应用深能级瞬态谱(DLTS)技术详细研究分子束外延(MBE)和金属有机物化学汽相淀积(MOCVD)生长的AlGaAs/GaAs graded index sparate confinement beterostruc-ture single quantum well(GRIN-SCH SQW)激光器的深中心.结果表明,在激光器的n-ALGaAs层里除众所周知的DX中心外,还存在着较大浓度和俘获截面的深(电子或空穴) 陷阱,它们直接影响着激光器的性能.其中MBE生长的激光器里的深空穴陷阱H1可能分布在x_(A1)=0.22→0.43和x (A1)=0.43的n-AlGaAs层里x_(A1)值不连续的界面附近,而深电子陷阱E3则可能分布在x_(A1)=0.43的n-AlGaAs层里x_(A1)值不连续的界面附近.MOCVD生长的激光器量子阱的AlGaAs层存在着DX中心和深电子陷阱.其中深电子陷阱E3可能分布在x_(A1)=0.22→0.30和x_(A1)=0.30的n-AlGaAs层里,而DX中心则分布在x_(A1)(x_(A1)=0.22→0.30和x_(A1)=0.30)值不连续的n-AlGaAs层界面附近.     

分子束外延生长的赝配高电子迁移率晶体管结构中深能级的研究

应用深能级瞬态谱(DLTS)技术详细研究分子束外延生长的Pseudomorphic—high electron mobility transistor(P-HEMT)结构中深能级行为。样品的DLTS表明,在P-HEMT结构的n-AlGaAs层里存在着较大浓度(10¹⁵-10¹⁷cm^-3和俘获截面(10^-16cm²)的高温电子陷阱。它们直接影响着器件性能。高温电子陷阱的产生可能与AlGaAs层里的氧     

分子束外延生长赝配高电子迁移率超高速微结构功能材料里深中心识别

应用深能级瞬态谱(DLTS)技术研究分子束外延(MBE)生长的highelectronmobilitytransistors(HEMT)和Pseudomorphichighelectronmobilitytransistors(PHEMT)结构深中心行为.样品的DLTS谱表明,在HEMT和PHEMT结构的nAlGaAs层里存在着较大浓度(1015-1017cm-3)和俘获截面(10-16cm2)的近禁带中部电子陷阱.它们可能与AlGaAs层的氧含量有关.同时还观察到PHEMT结构晶格不匹配的AlGaAsInGaAsGaAs系统在AlGaAs里产生的应力引起DX中心(与硅有关)能级位置的有序移动.其移动量可作为应力大小的一个判据,表明DLTS技术是定性识别此应力的可靠和简便的工具. 关键词： 分子束外延生长 高电子迁移率超高速微结构功能材料 深中心     

p型硅MOS结构Si/SiO2界面及其附近的深能级与界面态

用深能级瞬态谱(DLTS)技术系统研究了Si/SiO₂界面附近的深能级和界面态。结果表明,在热氧化形成的Si/SiO₂界面及其附近经常存在一个浓度很高的深能级,它具有若干有趣的特殊性质,例如它的DLTS峰高度强烈地依赖于温度,以及当栅偏压使费密能级与界面处硅价带顶的距离明显小于深能级与价带顶的距离时,仍然可以观测到一个很强的DLTS峰。另外,用最新方法测量的Si/SiO₂界面连续态的空穴俘获截面与温度有关,而与能量位置无明显关系,DLTS测 关键词：     

注硅半绝缘GaAs的深能级

用深能级瞬态谱(DLTS)详细研究了硅离子注入Liquid-encapsulated Czochralski(缩写为LEC)半绝缘GaAs的深中心。结果表明,在注硅并经高温退火的有源区中观测到4个多子(电子)陷阱,E₀₁,E₀₂,E₀₃和E₀₄。它们的电子表观激活能分别为0.298,0.341,0.555和0.821eV。其中E₀₄与EL2有关,但不是EL2缺陷。E₀₄的电子 关键词：     

注氮GaAs中的深能级及其对自由载流子的补偿

详细研究了注氮n型GaAs中深的和浅的杂质缺陷的电学性质。深能级瞬态谱(DLTS)技术测量表明,能量为140keV和剂量为1×10¹³cm^-2的氮离子注入并经800℃退火30min的GaAs中存在四个电子陷阱,E₁(0.111),E₂(0.234),E₃(0.415),E₄(0.669)和一个空穴陷阱H(0.545),而在能量为20keV和剂量为5×10^{14关键词：}     

p型硅MOS结构Si/SiO_2界面及其附近的深能级与界面态

用深能级瞬态谱(DLTS)技术系统研究了Si/SiO_2界面附近的深能级和界面态。结果表明,在热氧化形成的Si/SiO_2界面及其附近经常存在一个浓度很高的深能级,它具有若干有趣的特殊性质,例如它的DLTS峰高度强烈地依赖于温度,以及当栅偏压使费密能级与界面处硅价带顶的距离明显小于深能级与价带顶的距离时,仍然可以观测到一个很强的DLTS峰。另外,用最新方法测量的Si/SiO_2界面连续态的空穴俘获截面与温度有关,而与能量位置无明显关系,DLTS测量的界面态能量分布与准静态C-V测量的结果完全不一致。本文提出的Si/SiO_2界面物理模型能合理地解释上述问题。     

赝配GaAs/In0.2Ga0.8As量子阱导带不连续量的C-V和电容瞬态测量

分别采用二种不同方法测量分子束外延(MBE)生长GaAs/In_0.2Ga_0.8As单量子阱结构的导带不连续量ΔE_c:1) 考虑样品界面电荷修正的电容-电压(C-V)分布；2) 量子阱载流子热发射产生的电容瞬态(DLTS).C-V测得的ΔE_c=0.227eV,大约相当于89% ΔE_g.DLTS测得的ΔE_c=0.229eV,大约相当于89.9% ΔE_g.结果 关键词：     

Snapback应力引起的90 nm NMOSFET's栅氧化层损伤研究

实验结果发现突发击穿(snapback)，偏置下雪崩热空穴注入NMOSFET栅氧化层，产生界面态，同时空穴会陷落在氧化层中.由于栅氧化层很薄，陷落的空穴会与隧穿入氧化层中的电子复合形成大量中性电子陷阱，使得栅隧穿电流不断增大.这些氧化层电子陷阱俘获电子后带负电，引起阈值电压增大、亚阈值电流减小.关态漏泄漏电流的退化分两个阶段：第一阶段亚阈值电流是主要成分，第二阶段栅电流是主要成分.在预加热电子(HE)应力后，HE产生的界面陷阱在snapback应力期间可以屏蔽雪崩热空穴注入栅氧化层，使器件snapback开态和关态特性退化变小. 关键词： 突发击穿 软击穿 应力引起的泄漏电流 热电子应力     

Deep level transient spectroscopy in Hg1−xCdxTe

We report the application of Deep Level Transient Spectroscopy (DLTS) in Hg_1-xCd_xTe, demonstrating for the first time the utilization of DLTS techniques in a narrow band-gap semiconductor, E_g < 0.40 eV. DLTS measurements performed on an n⁺-p diode with E_g (x=0.21, T=30 K) =0.096 eV have identified an electron trap with an energy of E_v + 0.043 eV and a hole trap at E_v + 0.035 eV. Measurements of trap densities, capture cross sections, and the close proximity of the electron and hole trap locations within the band-gap suggest that DLTS may be observing both the electron and hole capture at a single Shockley-Read recombination center. The trapping parameters measured by DLTS predict minority carrier lifetime versus temperature data to be comparable with the experimentally measured values.     

同质硅分子束外延层的界面缺陷的研究

对同质硅分子束外延层的界面缺陷进行了测试与分析．对存在高浓度施主型界面缺陷的Ｐ型材料，通过解泊松方程计算了该材料的肖特基势垒的能带图，得到了该缺陷能级上电子的填充与发射随外加反向偏压变化的情况．并分析了用深能级瞬态谱（ＤＬＴＳ）对其进行测试所需的条件，以及与常规的ＤＬＴＳ测试结果的不同之处．提出了可同时对该缺陷上电子的发射和俘获过程进行ＤＬＴＳ测量的方法．实验测量结果表明，该高密度的界面缺陷的能级位置位于Ｅ_c－０．３０ｅＶ． 关键词：     

分子束外延生长GaAs/Si异质结电学特性的研究

利用样品Au-GaAs/p-Si的肖特基势垒二极管特性和深能级瞬态谱(DCTS),研究Si衬底上分子束外延生长的GaAs异质结的电学特性。I-V特性表明样品有大的漏电流存在,而快速热退火处理则能使样品I-V特性得以改善,并接近半绝缘GaAs(S.I.GaAs)上生长的Au-GaAs/S.I.GaAs样品的特性,它的来源不是热电子发射或产生-复合电流所引起,而可归结于缺陷参与的隧穿机制,它可通过快速热退火处理得以减小。DCTS谱表明在样品中可观察到Ec-0.41eV和Ec-0.57eV两个电子陷阱,前者可能 关键词：     

Photoluminescence study in step-graded composition InxAl1−xAs/GaAs

We report on the lattice-mismatched growth of step-graded In_xAl_1−xAs buffer layers on GaAs (0 0 1) substrates by molecular beam epitay (MBE). The approach to growing highly lattice-mismatched epilayers is to interpose a buffer layer between the substrate and the active layer. Two samples G30 and G40 with active layer compositions, respectively, x = 0.46 and x = 0.41, are studied by photoluminescence (PL). At low temperature, the PL spectra show a large broadened band whose energy and intensity depend on the active layer composition. The step-graded layer compositions improved the crystalline quality of these structures and increase the active layer PL band intensity.     

Photoluminescence of AlxGa1−xAs/GaAs quantum well heterostructures grown by molecular beam epitaxy

Low-temperature photoluminescence measurements on nominally undoped Al_xGa_1–xAs/GaAs quantum well heterostructures (QWHs) grown by molecular beam epitaxy (MBE) exemplified the exclusivelyintrinsic free-exciton nature of the luminescence under moderate excitation conditions. Neither any spectroscopic evidence for alloy clustering in the Al_xGa_1–xAs barriers nor any extrinsic luminescence due to recombination with residual acceptors has been detected in single and double QWHs when grown at 670 °C under optimized MBE growth conditions. Carrier confinement in Al_xGa_1–xAs/GaAs QWHs starts at a well width ofL _z30 nm when x0.25. The minor average well thickness fluctuation ofL _z=4×10^–2nm as determined from the excitonic halfwidth allowed the realization of well widths as low asL _z=1 nm and thus a shift of the free-exciton line as high as 2.01 eV which is close to the conduction band edge of the employed Al_0.43Ga_0.57As confinement layer. The measurements further revealed a strongly enhanced luminescence efficiency of the quantum wells as compared to bulk material which is caused by the modified exciton transition probabilities due to carrier localization.     

A digital-alloy AlGaAs/GaAs distributed Bragg reflector for application to 1.3μm surface emitting laser diodes

A distributed Bragg reflector (DBR) utilizing the digital alloy Al_0.9Ga_0.1As was grown by using the molecular beam epitaxy (MBE) method for application in 1.3 μm optical communications and compared to the analog-alloy AlGaAs/GaAs DBR. The transmission electron microscopic (TEM) image showed a highly abrupt boundary of AlAs and GaAs, which supports the formation of a digital-alloy Al_0.9Ga_0.1As layer. The measurement showed that the digital-alloy AlGaAs/GaAs DBR had similar reflection spectra with enhanced uniform distribution over the whole substrate surface compared to the analog-alloy one. In the digital-alloy Al_0.9Ga_0.1As/GaAs DBR cavity, the reflection dip position was measured at around 1273 nm and the standard deviation of the distribution of the reflection dip was 1.31 nm in wavelength over 1/4 of a three-inch wafer.     

Photoluminescence characterization of air exposed AlGaAs surface and passivated ex situ by ultrathin silicon interface control layer

Using the photoluminescence surface state spectroscopy (PLS³) technique, attempts were made to determine the surface state density (N_ss) distribution on Al_xGa_1−xAs (x≈0.3) surfaces passivated by the Si interface control layer (ICL) technique. Air-exposed AlGaAs epitaxial wafers which are technologically important for fabrication of various devices were passivated ex situ by forming a SiO₂/Si₃N₄/Si ICL/AlGaAs structure after the HCl treatment and their photoluminescence behavior was investigated in detail. The result of the PLS³ analysis indicated that Si ICL-based passivation reduces the minimum interface state density value down to 10¹⁰ cm⁻² eV⁻¹ range. Some indication was also obtained that further improvements are possible by using electron cyclotron resonance (ECR)-enhanced N₂ plasma for Si₃N₄/Si ICL interface formation.     

稳定的GaAs (2 5 1 1)高密勒指数表面的电子结构

采用格林函数方法对具有稳定结构的GaAs(2 5 11)(1×1)表面的电子结构特性进行了计算. 结果表明：对于理想的GaAs(2 5 11)表面，基本带隙内的表面态主要处在三个能量区域，即 -0.1—0.1eV，085—10eV和1.4—1.6eV之间；吸附两个As原子形成(1×1)再构后，表面态的变化主要表现在0.85—1.0eV之间的表面态完全消失.结合电子数目规则，可以确定处在 - 0.1—0.1eV之间的表面态为全部填满的阴离子悬挂键态或再构引起的As As二聚体键的表 面态，而处在1.4— 关键词： 高密勒指数表面 电子结构 电子数目规则