用MOCVD方法制备的GaN_(1-x)P_x三元合金的喇曼与红外光谱

采用光辐射加热低压金属有机化学气相淀积(L P- MOCVD)方法在蓝宝石衬底上生长了高P组分的Ga N1 - x-Px 三元合金薄膜,通过喇曼光谱和红外反射谱技术研究了Ga N1 - x Px 合金中P掺杂所引入的振动模.与非掺P的Ga N相比,在Ga N1 - x Px 合金的喇曼谱和红外反射谱中分别观测到了多个由P所引入的振动模,文中将它们分别归因于Ga- P键振动引起的准局域模、间隙模以及P掺入造成的局部晶格无序激活的振动模     

Optical phonons in CdGa2S4x Se4(1 − x) alloys

The Raman spectra of CdGa₂S_4x Se_{4(1 ? x)} alloys (x = 0.1, 0.2, … 0.9) are studied. Both the singlemode and double-mode behavior of optical phonons are observed in CdGa₂S_4x Se_{4(1 ? x)} alloys. The observed optical mode at 138 cm^?1 is independent of the composition. It seems likely that this mode is the “breathing mode” and is caused by atomic motion in the anion sublattice relative to vacancies. It is shown that the high-frequency modes of symmetry B ₁(LO, TO) and B ₂(LO, TO) are caused by the in-phase motion of atoms in the anion sublattice along the tetragonal axis c relative to trivalent Ga atoms. The doubly degenerate symmetry modes E ₁(LO, TO) and E ₂(LO, TO) are caused by the in-phase motion of atoms in the anion sublattice relative to trivalent Ga atoms of the cation sublattice in the xy plane (dipole 2Ga–4C), where C is S, Se. The optical symmetry modes B ₃(LO, TO) and B ₄(LO, TO) are associated with the motion of atoms in the anion sublattice relative to Cd atoms along the tetragonal axis c. The doubly degenerate modes E ₃(LO, TO) and E ₄(LO, TO) are associated with the motion of atoms in the anion sublattice relative to Cd atoms (dipole Cd–4C). The low-frequency modes B ₅(LO, TO) and E ₅(LO, TO) are the analogs of acoustic phonons at the edge of the Brillouin zone of sphalerite.     

碲镉汞体材料的显微Raman光谱

利用Raman显微镜测量了ACRT-Bridgman方法和Te溶剂方法生长的碲镉汞体材料的显微Raman光谱，在碲镉汞体材料的显微Raman光谱中识别出了碲镉汞的基本光学振动模，由此证明了碲镉汞按晶格振动的分类方法属于二模混晶；识别出了一个来源于类HgTe的TO1模 LO1模的二级Raman散射峰；观察到了碲镉汞体材料中两个新的Raman散射峰，分别位于662cm^-1和749cm^-1；观察到了碲镉汞基本光学振动模的TO1模与LO1模的Raman散射强度比的变化，指出该现象是由于Raman散射几何配置不同引起的。     

纳米碳管模板法制取的GaP纳米棒拉曼光谱研究

报道了用纳米碳管模板法制备的GaP纳米棒的拉曼光谱特征，观测到声子限制效应引起的GaP纳米棒TO和LO模的红移，红移量一般在2－10cm^-1之间，与所测到的纳米棒的尺寸有关，在偏振特性研究中，发现GaP纳米棒的偏振特性不能用单根纳米棒的选择定则来解释，而与测量光斑内多根纳米棒的无序取向有关，无序程度越高，偏振特性的方向性越弱，当激发光功率增加时，GaP纳米棒的TO和LO模的频率显著减少，表明纳米棒中的激光加热效应比体材料中强很多，而且GaP纳米棒的拉曼散射强度随激发光功率的增加先饱和，然后减小，表明在强激发功率下GaP纳米棒中的缺陷会迅速增加。     

Low-threshold semiconductor Raman laser

A semiconductor Raman laser using the longitudinal optical (LO) phonon mode of GaP has a very low threshold compared to the transverse optical (TO) phonon mode of GaP and even compared to simulated Raman scatterings in various kinds of liquids and insulating solid materials. The lowest threshold value of the pulsed input optical power is 8 kW (5 times 10^{6}W/cm²) at room temperature. Far infrared radiation (24.8 μm) has been generated by placing both GaP with the LO phonon mode and GaAs with the TO phonon mode in a Fabry-Perot resonator. The maximum far infrared power has been 3 W.     

Infrared reflectivity studies of gax in1-x asy p1-y quaternary compounds

Reflectivity spectra have been measured on Ga_xIn_1-xAS_yP_1-y quaternary alloys, lattice-matched to InP substrates, covering the complete composition range from y = 0 (InP) to y = 1 (Ga_0.47 In_0.53 As). The spectra have been analysed to obtain parameters of both the free carriers and lattice vibrations. The reflectivity method has been used to measure the carrier density and mobility, the relatively low mobilities obtained confirming the electrical measurements explained previously by the presence of strong alloy scattering in this system. Four phonon modes, corresponding to InAs-, GaAs-, InP- and GaP-like vibrations, were observed over most of the composition range, except for y ≲ 0.25 where the GaAs mode was not observed and the GaP mode was a weak mode within the reststrahlen band of the InP mode. Thus the behaviour of the system may be termed "two"-four mode. The oscillator strengths of the four modes are consistent with this behaviour and their variation may be explainable by assuming that Ga_xIn_1-xAS_yP_1-y is a random alloy.     

HBT结构的新进展

介绍了以In0.03Ga0.97As0.99N0.01材料为基区的GaAs异质结双极型晶体管和以GaAs0.51Sb0.49材料为基区的InP HBT.讨论了GaAs和InP HBT结构的新进展及其对性能的改善,并对各结构的适用范围和优缺点进行了比较.     

(Al x Ga 1- x ) y In 1- y P Films and Its Optical Constants on the Surface

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分子束外延Hg0.68Cd0.32Te薄膜光致发光和喇曼散射的研究

对利用ＭＥＢ技术生长的Ｈｇ０．６８Ｃｄ０．３２Ｔｅ薄膜进行了光致发光和喇曼光谱的研究，拟合薄膜光致发光谱得到的禁带宽度，与红外透射谱得到的薄膜带宽相近；其半宽仅为５ｍｅＶ，带尾能量小于１．３ｍｅＶ，显示了较高的薄膜质量。     

Raman scattering in (111) strained heterostructures

III–V based strained heterostructures grown along [hhk] directions are considered. The proportionality coefficients between the in-plane strain and the shift in the TO and LO phonon frequencies have been calculated from the elastic constants and phonon deformation potentials. GaAs/GaP (111) and GaAs/InP (111) systems, where the GaAs epitaxial layers are in compressive or tensile strain, respectively, have been grown by MOVPE at different times on A and B substrates and investigated by Raman scattering. The corresponding red or blue shifts of the frequencies of the LO and TO phonons are measured and the residual strain parallel to the interface is estimated. The Raman results are discussed on the basis of the morphology of the epilayer investigated by atomic force microscopy.     

（n11）面上生长的Ⅲ—Ⅴ族半导体的喇曼散射研究

报道不同指数面（ｎ１１）上生长的Ｇａ０．５Ａｌ０．５Ａｓ 和Ｉｎ０．５２Ａｌ０．４８Ａｓ系列样品的长光学声子模的室温喇曼散射测量结果．在背散射条件下不同的偏振配置下,观测到这些样品中对应的Ｌ０ 模和Ｔ０ 模的相对强度随着不同的指数面呈现出规律变化,同时把这一实验结果与（ｎ１１）指数面上生长的闪锌矿结构材料的喇曼散射选择定则的理论预计相比较,实验结果与理论预期的一致     

Calculated threshold currents of nitride- and phosphide-based quantum-well lasers

We have calculated the room temperature gain-current characteristics for a 360 nm wavelength, 80 /spl Aring/ GaN-Al/sub 0.14/Ga/sub 0.86/N and a red-emitting, 80 /spl Aring/ Ga/sub 0.51/In/sub 0.49/P-(Al/sub 0.44/Ga/sub 0.56/)/sub 0.51/In/sub 0.49/P quantum well laser structures, including many body effects. Although the carrier density and spontaneous current are much higher (by a factor of 4 and 3, respectively) in the nitride structures for a given local gain, the higher confinement factor at short wavelengths means the intrinsic threshold current of these devices is predicted to be approximately twice that of red lasers with the same optical loss.     

基于低温In_xGa_(1-x)P组分渐变缓冲层的InP/GaAs异质外延

采用低温GaAs与低温组分渐变InxGa1-xP作为缓冲层,利用低压金属有机化学气相外延(LP-MOCVD)技术,在GaAs(001)衬底上进行了InP/GaAs异质外延实验。实验中,InxGa1-xP缓冲层选用组分线性渐变生长模式(xIn0.49→1)。通过对InP/GaAs异质外延样品进行双晶X射线衍射(DCXRD)测试,并比较1.2μm厚InP外延层(004)晶面ω扫描及ω-2θ扫描的半高全宽(FWHM),确定了InxGa1-xP组分渐变缓冲层的最佳生长温度为450℃、渐变时间为500s。由透射电子显微镜(TEM)测试可知,InxGa1-xP组分渐变缓冲层的生长厚度约为250nm。在最佳生长条件下的InP/GaAs外延层中插入生长厚度为48nm的In0.53Ga0.47As,并对所得样品进行了室温光致发光(PL)谱测试,测试结果表明,中心波长为1643nm,FWHM为60meV。     

SiO2薄膜TO与LO振动模式的数值研究

对Si-SiO2基底薄膜系统进行数值实验,将SiO2薄膜的能损函数与透过率光谱和反射椭圆偏振光谱进行对比,讨论了在红外透过率光谱和反射椭偏光谱中激发的SiO2薄膜TO和LO振动模式.在正入射的红外透过率光谱中,仅能发现SiO2薄膜的TO振动模式;在倾斜入射的s偏振透过率光谱中没有激发的LO模式;在倾斜入射的p偏振透过率光谱中,当入射角小于60时,三个TO振动模式全部被激发;当入射角大于60时,三个LO振动模式都被激发,而TO模式仅能激发两个.在反射椭偏光谱中,TO模式未被激发,仅能激发LO模式.在透过率光谱和反射椭偏谱中,振动频率分别具有向高波数和低波数方向频移的现象.     

0.66 ?m room-temperature operation of InGaAlP DH laser diodes grown by MBE

Room-temperature pulsed operation of In0.49Ga0.31Al0.20P/In0.49Ga0.48Al0.03P/In0.49Ga0.31Al0.20P double heterostructure (DH) laser diodes has been achieved for the first time. The DH layers were grown by molecular beam epitaxy. The lasing wavelength was 0.66 ?m and the threshold current density was 3.2?3.6 × 104 A/cm2 at room temperature.     

用拉曼散射谱与远红外反射谱研究Ga_xIn_(1-x)As_ySb_(1-y)四元混晶的长波光学声子

报道了 MBE外延生长的 Gax In1 - x Asy Sb1 - y四元混晶的拉曼散射谱与远红外反射谱 ,并从拉曼散射谱中观察到了 Gax In1 - x Asy Sb1 - y四元混晶的晶格振动四模行为 ;从实验中还观察到低于 180 cm- 1的若干散射峰 ,提出它们可能是与次近邻原子间相互作用的晶格振动模式有关 ;从拉曼散射谱和红外反射谱中观察到了与 Gax In1 - xAsy Sb1 - y四元混晶多声子吸收过程的有关的现象     

InP与In_（1－x）Ga_xAs_yP_（1－y）／InP的电解液电调制反射

研究了ＩｎＰ样品和Ｉｎ１－ｘＧａｘＡｓｙＰ１－ｙ液相外延片在３００～８００ｎｍ范围内的电调制反射光谱。利用Ａｐｓｎｅｓ三点法计算了临界点能量、增宽因子和自旋轨道分裂值。通过实验曲线与理论公式的拟合，确定了临界点能维数及相位因子。并且间接提供了被测Ｉｎ１－ｘＧａｘＡｓｙＰ１－ｙ四元合金的组份值及其它临界点能量值Ｅ０和Ｅ２。     

InP衬底上Ga_(0.47)In_(0.53)As/InP液相外延生长

用液相外廷获得了与InP晶格匹配的Ga_(0.47),In_(0.53)As单晶外延层.本文叙述在(100)和(111)InP衬底上Ga_(0.47)In_(0.53)As/InP液相外延生长方法.用常规滑动舟工艺生长的这种外延层,其表面光亮,Ga的组分x=0.46～0.48,晶格失配率小于2.77×10~(-4),禁带宽度E_g=0.74～0.75eV.使用这种Ga_(0.47)In_(0.53)As/InP/InP(衬底)材料研制的长波长光电探测器,在波长为0.9～1.7μm范围内测出了光谱响应曲线,在1.55μm处呈现峰值.     

Non-blocking collector InP/GaAs0.51Sb0.49/InPdouble heterojunction bipolar transistors with a staggered lineupbase-collector junction

We have developed lattice-matched InP/GaAs_0.51Sb_0.49/InP NpN double heterojunction bipolar transistors (DHBTs) which take advantage of the staggered (“type II”) band lineup at InP/GaAs_0.51Sb_0.49 interfaces: in this system the GaAs_0.51Sb_0.49 base conduction band edge lies ~0.18 eV above the InP collector conduction band, thus enabling the implementation of InP collectors free of the current blocking effect encountered in conventional Ga_0.47In_0.53As base DHBTs. The structure results in very low collector current offset voltages, low emitter-base turn-on voltages, and very nearly ideal base and collector current characteristics with junction ideality factors of n_B=1.05 and n_c=1.00. InP/GaAs_0.51Sb_0.49/InP DHBTs appear well-suited to low-power applications, but can also be used in power applications by virtue of their InP collector. The symmetry of the transistor band structure also lends itself to the potential integration of collector-up and emitter-up devices     

退火对Zn扩散的影响及其在InGaAs探测器中的应用

采用闭管扩散方式,对不同结构的异质结外延材料In0.81Al0.19As/In0.81Ga0.19As、InAs0.6P0.4/In0.8Ga0.2As、InP/In0.53Ga0.47As实现了Zn元素的P型掺杂,采用扫描电容显微技术(SCM)和二次离子质谱(SIMS)研究了在芯片制备中高温快速热退火(RTP)处理环节对p-n结结深的影响。结果表明:由于在这3种异质结外延材料中掺杂的Zn元素并未完全激活,导致扩散深度明显大于p-n结结深;高温快速热退火处理并不会显著影响结深的变化,扩散完成后的p-n结深度可以近似为器件最终的p-n结结深;计算了530℃下Zn在In0.81Al0.19As、InAs0.6P0.4、InP中的扩散系数D分别为1.327×10-12cm2/s、1.341 10-12cm2/s、1.067×10-12cm2/s。