全固源分子束外延生长InP和InGaAsP

在国产分子束外延设备的基础上,利用新型三温区阀控裂解源炉,对InP及InGaAsP材料的全固源分子束外延(SSMBE)生长进行了研究.生长了高质量的InP外延层,表面缺陷密度为65cm-2,非故意掺杂电子浓度约为1×1016cm-3.InP外延层的表面形貌、生长速率及p型掺杂特性与生长温度密切相关.研究了InGaAsP外延材料的组分特性,发现在一定温度范围内生长温度对Ⅲ族原子的吸附系数有较大影响.最后得到了晶格匹配的In0.56Ga0.4As0.04P06材料,低温光致发光谱峰位于1507 nm,FWHM为9.8 meV.     

InP外延材料的MBE生长模式

采用固态磷源分子束外延技术,在不同的生长条件下生长了InP外延材料,并用原子力显微镜对样品表面形貌进行了系统研究.实验结果表明,样品表面形貌的显著变化与生长模式发生变化有关;二维(2D)生长模式和三维(3D)生长模式之间存在转换的临界工艺条件.通过对实验数据的分析,绘制了InP外延生长模式对应工艺条件的区域分布图;在2D生长区域获得了高质量的InP/InP外延材料.     

InP外延材料的MBE生长模式

采用固态磷源分子束外延技术,在不同的生长条件下生长了InP外延材料,并用原子力显微镜对样品表面形貌进行了系统研究.实验结果表明,样品表面形貌的显著变化与生长模式发生变化有关;二维(2D)生长模式和三维(3D)生长模式之间存在转换的临界工艺条件.通过对实验数据的分析,绘制了InP外延生长模式对应工艺条件的区域分布图;在2D生长区域获得了高质量的InP/InP外延材料.     

在n—InP(100)衬底上低温液相外延生长1.55μm GaInAsP双异质结构层的研究

在590℃温度下,不使用1.3μm GaInAsP 防回熔层,直接在 n-InP(100)衬底上液相外延生长出1.55μm InP/GaInAsP/InP 双异质结构外延片。对这种外延片的生长情况及其特性和 InP 衬底的热损伤情况,本文作了详细的分析和讨论。     

InGaAsP／InP激光器非平面液相外延生长的研究

本文叙述了用于制作 InGaAsP/InP 半导体激光器的非平面液相外延工艺。讨论了各种因素对非平面液相外延生长的影响。在 InP 衬底上和刻有沟槽的 InGa-AsP/InP 外延片上成功地生长出了高质量外延层。用该外延片制作的激光器在室温连续工作条件下典型阈值电流30mA,典型输出功率为10mW。最高激射温度为115℃。     

基于MOCVD的InP/GaAs异质外延生长

使用金属有机物气相沉积方法(MOCVD),在GaAs衬底上生长InP外延层.先在GaAs衬底上生长一层低温InP缓冲层,然后再生长InP外延层.通过比较不同缓冲层生长条件下的外延层晶体质量,发现在生长温度为450℃,厚度约15nm的缓冲层上外延所得到的晶体质量最理想;此外,外延层厚度的增加对其晶体质量有明显改善作用.实验在优化生长条件的同时,也考虑了热退火等辅助工艺,最后所获得的外延层的双晶X射线衍射(DCXRD)的ω/2θ扫描外延峰半高全宽(FWHM)值为238.5".     

基于MOCVD的InP/GaAs异质外延生长

使用金属有机物气相沉积方法(MOCVD),在GaAs衬底上生长InP外延层.先在GaAs衬底上生长一层低温InP缓冲层,然后再生长InP外延层.通过比较不同缓冲层生长条件下的外延层晶体质量,发现在生长温度为450℃,厚度约15nm的缓冲层上外延所得到的晶体质量最理想;此外,外延层厚度的增加对其晶体质量有明显改善作用.实验在优化生长条件的同时,也考虑了热退火等辅助工艺,最后所获得的外延层的双晶X射线衍射(DCXRD)的ω/2θ扫描外延峰半高全宽(FWHM)值为238.5".     

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。     

基于异变缓冲层与应变层超晶格的InP/GaAs异质外延

利用低压金属有机化学气相沉积技术, 开展InP/GaAs异质外延实验。由450 ℃生长的低温GaAs层与超薄低温InP层组成双异变缓冲层, 并进一步在正常InP外延层中插入In1-xGaxP/InP(x=7.4%)应变层超晶格。在不同低温GaAs缓冲层厚度、应变层超晶格插入位置及应变层超晶格周期数等条件下, 详细比较了InP外延层(004)晶面的X射线衍射谱, 还尝试插入双应变层超晶格。实验中, 1.2 μm和2.5 μm厚InP外延层的ω扫描曲线半峰全宽仅370 arcsec和219 arcsec; 在2.5 μm厚InP层上生长了10周期In0.53Ga0.47As/InP 多量子阱, 室温PL谱峰值波长位于1625 nm, 半峰全宽为60 meV。实验结果表明, 该异质外延方案有可能成为实现InP-GaAs单片光电子集成的一种有效途径。     

InGaAs／InP SAGM—APD结构的液相外延生长研究

本文讨论了InP/InGaAsP/InGaAs/InP SAGM-APD结构的抗回熔生长,并解决了InP在InGaAs上液相外延生长时的回熔问题。同时,研究了各外延层参数的控制。结果制得的器件,其最大雪崩倍增20,0.9V_B下暗电流14nA,响应度大于0.6A/W。     

Novel In0.52Al0.48As/In0.53Ga0.47As metamorphic high electron mobility transistors on GaAs substrate with InxGa1−xP graded buffer layers

Compositionally graded In_xGa_1−xP (x=0.48→x=1) metamorphic layers have been grown on GaAs substrate by solid source molecular beam epitaxy using a valved phosphorus cracker cell. Three series of samples were grown to optimize the growth temperature, V/III ratio and grading rate of the buffer layer. X-ray diffraction (XRD) and photoluminescence (PL) were used to characterize the samples. The following results have been obtained: (1) XRD measurement shows that all the samples are nearly fully strain relaxed and the strain relaxation ratio is about 96%; (2) the full-width at half-maximum (FWHM) of the XRD peak shows that the sample grown at 480°C offers better material quality; (3) the grading rate does not influence the FWHM of XRD and PL results; (4) adjustment of the V/III ratio from 10 to 20 improves the FWHM of XRD peak, and the linewidth of PL peak is close to the data obtained for the lattice-matched sample on InP substrate. The optimization of growth conditions will benefit the metamorphic HEMTs grown on GaAs using graded InGaP as buffer layers.     

Low-temperature growth of nitrogen-doped BeTe and ZnSe/BeTe:N superlattices for delta doping

We propose ZnSe/BeTe:N superlattice (SL) as a new p-type cladding layer with improved p-type dopability, in which nitrogen-doped BeTe (N-doped) layers are inserted into undoped ZnSe layers. We have optimized the growth temperature for ZnSe/BeTe:N SLs. Both equivalent beam pressure (BEP) ratio and growth rate are further optimized in low-temperature growth of BeTe:N layers. The structural properties of BeTe:N layers were analyzed by reflection high-energy electron diffraction and high-resolution X-ray diffraction. Electrical properties were evaluated by the van der Pauw method and capacitance–voltage (C–V) measurements. We achieve the net acceptor concentrations of 1.2×10¹⁹ cm⁻³ at the growth temperature of 350°C, BEP ratio of around 6, and growth rate of 35 nm/h.     

MBE生长InGaAs／GaAs应变层单量子阱激光器结构材料的研究

采用ＶａｒｉａｎＧｅｎⅡＭＢＥ生长系统研究了ＩｎＧａＡｓ／ＧａＡｓ应变层单量子阶（ＳＳＱＷ）激光器结构材料。通过ＭＢＥ生长实验，探索了Ｉｎ＿ｘＧａ＿（１－ｘ）ｔＡｓ／ＧａＡｓＳＳＱＷ激光器发射波长（λ）与Ｉｎ组分（ｘ）和阱宽（Ｌ＿ｚ）的关系，并与理论计算作了比较，两者符合得很好。还研究了材料生长参数对器件性能的影响，主要包括：Ⅴ／Ⅲ束流比，量子阱结构的生长温度Ｔ＿ｇ（ＱＷ），生长速率和掺杂浓度对激光器波长、阈值电流密度、微分量子效率和器件串联电阻的影响。以此为基础，通过优化器件结构和ＭＢＥ生长条件，获得了性能优异的Ｉｎ＿（０．２）Ｇａ＿（０．８）Ａｓ／ＧａＡｓ应变层单量子阱激光器：其次长为９６３ｎｍ，阈值电流密度为１３５Ａ／ｃｍ￣２，微分量子效率为３５．１％。     

M-ary CPFSK-DPD with L-diversity maximum ratio combining in Ricianfast-fading channels

We derive a formula for the bit error probability (BEP) of M-ary continuous phase frequency shift keying with differential phase detection and maximum ratio combining diversity in Rician fast-fading channels. We assume that transmitter and receiver filters distort the signal and limit the noise. We compute the BEP as a function of energy-to-noise ratio per bit (E_b/N₀) and other system and channel parameters: Rician factor K=0, 6 dB, 10, ∞; number of diversity channels L=1, 2, 3; Doppler frequency shift f_D T=0, 0.01, 0.02; Butterworth filters in transmitter and receiver of order N_T=3 and N_R=4; optimal sampling time and filter bandwidth. In all cases the BEP is significantly reduced by diversity     

High growth rate process in a SiC horizontal CVD reactor using HCl

The results of a new epitaxial process using an industrial 6 × 2″ wafer reactor with the introduction of HCl during the growth have been reported. A complete reduction of silicon nucleation in the gas phase has been observed even for high silicon dilution parameters (Si/H₂ > 0.05%) and an increase of the growth rate until about 20 μm/h has been measured. Photoluminescence at room temperature and at 50 K was used for defects quantification and distribution. On these wafers grown using HCl high voltage Schottky diodes have been realized. The diodes were analyzed by current-voltage (I-V) characteristics.     

Investigations on indium phosphide grown by chemical beam epitaxy

In this paper, we present a systematic study of the properties of indium phosphide (InP) layers grown by chemical beam epitaxy (CBE). Trimethylindium (TMIn) and phosphine (PH₃) are used as source materials. The relation between the phosphine cracker temperature and the cracking efficiency has been studied by mass spectroscopy during growth. The growth rate and morphology of the layers have been studied by varying the TMIn and phosphine flow rates as well as the substrate temperature. We have found that, under a wide range of growth conditions, the deposition rate is only determined by and proportional to the TMIn flow rate. This is in agreement with literature. Additionally, we observe that the growth rate decreases below a certain phosphine to TMIn flow rate (V/III) ratio and becomes phosphine flow limited. From investigations of the growth rate as a function of temperature, it is concluded that the desorption of indium species from InP starts at a temperature slightly below 540°C. For this desorption process, we have found an activation energy of (217 ± 20) kJ/mol. Further characterization of the InP layers has been carried out by photoluminescence and Hall measurements. From both methods, the optimum growth conditions have been established. Under these conditions, we reproduc-ibly obtain InP layers showing linewidths of the donor-bound exciton transition at 5K around 0.25 meV and a mobility at 77K of about 7.0·10⁴ cm²/Vs. From the analysis of the mobility in the temperature range from 20 to 300K, we conclude that, additionally to shallow donors and acceptors, deep-donor centers with an activation energy of about 150 meV are present in all layers.     

GaSb衬底上分子束外延生长的低温GaSb薄膜的低缺陷表面

本论文系统的研究了,随着GaSb薄膜生长温度的降低,V/III比的变化对薄膜低缺陷表面质量的影响。为了获得良好表面形貌的GaSb外延层,生长温度与V/III比均需要同时降低。当Sb源裂解温度为900℃时,生长得到低缺陷表面的低温GaSb薄膜的最佳生长条件是生长温度为在再构温度的基础上加60℃且V/III比为7.1。     

Binary PRCPM with differential phase detection and maximal ratiocombining diversity in fading channels

We derive a formula for the bit-error probability (BEP) of binary partial-response continuous-phase modulation (PRCPM) with N-bit differential phase detection (DPD) in a Rician fading channel subject to L-branch maximum ratio combining (MRC) diversity. We compute the BEP for minimum-shift keying (MSK), Gaussian MSK (GMSK), and 2 RC (2-b-duration raised cosine) frequency signals as a function of the energy-to-noise ratio per bit E_b/N₀ and other system and channel parameters [N=1 and 2 and L=1, 2, and 3, Rician factor K=-∞, 0, 6, 10, and ∝ dB, Doppler frequency shift f_DT=0, 0.01, and 0.02, Gaussian premodulation filter bandwidth B_gT=∞, 0.5, 0.25, and the presence or absence of a Doppler frequency tracking loop (DFTL) in the receiver]. In all cases, the BEP is significantly reduced by diversity     

Some aspects of the RHEED behavior of low-temperature GaAs growth

The reflection high-energy electron diffraction (RHEED) behavior manifested during MBE growth on a GaAs(001) surface under low-temperature (LT) growth conditions is examined in this study. RHEED and its intensity oscillations during LT GaAs growth exhibit some particular behavior. The intensity, phase, and decay of the oscillations depend on the beam equivalent pressure (BEP) ratio and substrate temperature, etc. Here, the intensity dependence of RHEED behavior on the BEP ratio, substrate temperature, and excess of As content in the layer are examined. The change in the decay constant of the RHEED oscillations is also discussed.     

PVT法同质籽晶AlN晶体生长

为了获得高质量AlN晶体,通过物理气相传输(PVT)法,采用AlN籽晶进行AlN晶体生长,并通过双温区加热装置对衬底与原料之间的温差进行调节。研究结果表明,籽晶形核阶段,随着AlN籽晶与原料顶温差的减小,AlN的形核机制呈现三种模式,分别为岛生长模式、畴生长模式和螺旋位错生长模式;晶体生长阶段,通过增加AlN籽晶与原料顶温差来提高晶体生长速率,采用10℃/h的变温速率将温差从10℃增加为30℃时,AlN晶体生长模式不变,仍然保持螺旋位错生长模式,该生长模式下获得的AlN晶体结晶质量最高,(0002)面摇摆曲线半峰宽(FWHM)约为55 arcsec。