InGaAsSb/AlGaAsSb长波长多量子阱激光器有源区的优化设计

系统地研究了波长为2.7μm的InGaAsSb/AlGaAsSb多量子阱激光器中有源区的优化设计.分别用含应变势的6带KP模型和抛物带模型计算价带和导带的能带结构，并得到薛定谔方程和泊松方程的自洽解，由此计算量子阱在载流子注入时的增益谱.研究表明制约量子阱增益的主要因素不是跃迁矩阵元，而是粒子数反转程度，尤其是空穴填充HH1子带的概率.增加压应变或减小阱宽都会提高量子阱增益.前者降低了价带HH1子带空穴的平面内有效质量；后者拉大了价带子带间距，尽管它同时略微增加了空穴有效质量.这两种因素都导致价带顶空穴态     

(n)nc-Si：H/(p)c-Si异质结中载流子输运性质的研究

采用常规等离子体增强化学气相沉积工艺,以高H₂稀释的SiH₄作为反应气体源和PH₃作为磷原子的掺杂剂,在p型(100)单晶硅((p)c-Si)衬底上, 成功地生长了施主掺杂型纳米硅膜((n)nc-Si:H),进而制备了(n)nc-Si:H/(p)c-Si异质结,并在230—420Ｋ温度范围内实验研究了该异质结的Ｉ-Ｖ特性.结果表明,(n)nc-Si:H/(p)c- Si异质结为一典型的突变异质结构,具有良好的温度稳定性和整流特性.正向偏压下 关键词： (n)nc-Si:H/(p)c-Si异质结 能带模型 电流输运机构 温度特性     

掺杂纳米硅薄膜中电子自旋共振研究

研究了掺杂纳米硅薄膜(nc∶Si∶H)中的电子自旋共振(ESR)及与之相关的缺陷态.样品是用等离子体增强化学气相沉积方法制成,为两相结构,即纳米晶粒镶嵌于非晶本体之中.对掺磷的nc-Si∶H样品,测量出其ESR信号的g值为1.9990—1.9991,线宽ΔH_pp为(40—42)×10^-4T,ESR密度Nss为10¹⁷cm^-3数量级.对掺硼的nc-Si∶H样品,其ESR信号的g值为2.0076—2.0078,ΔH_{关键词： 纳米硅薄膜 微结构 电子自旋共振}     

Pulse Wavelength Scan of Room-Temperature Mid-Infrared Distributed Feedback Quantum Cascade Lasers for N2O Gas Detection

The tunable diode laser absorption spectroscopy under a pulse wavelength scan scheme is adapted to home-made room-temperature mid-infrared distributed feedback quantum cascade lasers; and identification of N2O spectral fingerprint is demonstrated experimentally. By driving the laser at 800ns pulse duration, a wave number tuning of about 1.6cm^-1 is produced, which make both 1289.04cm^-1 and 1289.86cm^-1 absorption fingerprints of N2O gas to be definitely assigned. The measured relative absorption intensity is consistent with the HITRAN data precisely.     

InGaAsSb／AIGaAsSb长波长多量子阱激光器有源区的优化设计

系统地研究了波长为2．7μm的InGaAsSb／AlGaAsSb多量子阱激光器中有源区的优化设计，分别用含应变势的6带KP模型和抛物带模型计算价带和导带的能带结构，并得到薛定谔方程和泊松方程的自洽解，由此计算量子阱在载流子注入时的增益谱，研究表明制约量子阱增益的主要因素不是跃迁矩阵元，而是粒子数反转程度，尤其是空穴填充HHl子带的概率，增加压应变或减小阱宽都会提高量子阱增益，前者降低了价带HHl子带空穴的平面内有效质量；后者拉大了价带子带间距，尽管它同时略微增加了空穴有效质量，这两种因素都导致价带顶空穴态密度的降低，提高了空穴在HHl子带的填充概率，最终提高了量子阱的增益，所得结论与已有的实验报道相符。     

Thermal Analysis of InAs/AlSb Short Wavelength Mid-IR Quantum Cascade Lasers

We present the effects of hetero-interfaces and major key parameters on the thermal behaviors and performance of short wavelength mid-IR InAs/AlSb quantum cascade lasers （QCLs）. We use a finite element method （FEM） with commercial software, ANSYS, to simulate the heat dissipation in QCLs in cw operation mode with an epilayer-down mounting package. The thermal performance is characterized by the temperature increase AT （self-heating effect） between the active region of QCLs and the heatsink. Results show that （1） the self-heating effects of InAs/AlSb QCLs are much less than those in AlInAs/GaInAs Q, CLs, （2） narrower ridges lead to significantly cooler active regions of InAs/AlSb QCLs due to poor heat transport in the cross-plane direction （across interfaces） and that most of the heat flows out of the active region in the lateral direction, and （3） the cavity length of the laser has little influence on the self-beating effect of the device, but the long cavity reduces mirror loss and threshold current density.     

基于掩埋光栅一级分布反馈结构的太赫兹量子级联激光器

结合理论和实验研究了掩埋光栅一级分布反馈太赫兹量子级联激光器中的模式竞争和功率特性。理论计算得到掩埋光栅腐蚀深度与两个带边模式的波导损耗、光学限制因子、辐射损耗以及辐射效率的关系。理论计算表明,掩埋光栅分布反馈结构可以通过改变腐蚀深度,保证激光器稳定单模工作在高频带边模式的同时,调节激光器的阈值增益以及辐射效率。实验和测试结果表明,激光器辐射波长和掩埋光栅的周期成正比,激光器可以在整个动力学范围内稳定单模工作。单模激光器的波长范围可覆盖86.2~91.7μm的范围,边模抑制比可达25 dB,最大输出功率为9.1 mW。该工作有助于高性能单模太赫兹激光器及锁相耦合激光器阵列的研制。     

量子级联激光器有源核中界面声子的特性研究

研究了量子级联激光器有源核中界面声子的色散关系和静电势分布. 根据有源核内部的平移不变性导出了界面声子的色散关系. 计算显示有源核中的界面声子可以分为体声子和表面声子模式. 体声子的色散曲线构成一系列准连续的声子子带，其静电势分布于整个有源核并呈现出Bloch波的特征. 表面声子的色散曲线位于各体声子子带的带隙内，其静电势局域在有源核一侧. 这些结果将有助于量子级联激光器和子带跃迁激光器的优化设计.     

Low Threshold Distributed Feedback Quantum Cascade Lasers with Widely Spaced Emission Wavelengths

We report lasing properties of distributed feedback quantum cascade lasers （DFB QCLs） including a doublephonon-resonance active region, at wavelength of about 8.4 μm. A broad gain spectrum is generated due to the coupling between the lower laser level in the active region and the levels in the injector, and is demonstrated by the lasing spectrum of the corresponding Fabry-Perot QCLs whose width is 0.5 μm at 1.5 times of the threshold current. As a result, the DFB QCLs employing different grating periods exhibit a wavelength span of 0.18μm at room temperature and total wavelength coverage of 0.28μm at various heat sink temperatures. A high side mode suppression ratio of about 30dB and a low threshold current density of 1.78kA/cm^2 are achieved as the lasers operate at room temperature in pulsed mode.     

Room—Temperature A1GaAsSb／InGaAsSb Multi—Quantum—Well Lasers with High Chraracteristic Temperature

Planar structure A1GaAsSb/InGaAsSb lasers operated at 2.01/zm with high characteristic temperature have been fabricated from a strained multiple quantum-well heterostructure. To decrease the free carrier induced absorption of optical mode in the mid-infrared, we design a broaden waveguide layer in the laser structures to decrease the optical mode distribution in the heavy doped cladding layer, therefore it can be absorbed easily. To enhance the characteristic temperature of laser diodes, A1 constituent up to 80% was applied to the A1GaAsSb cladding layer. The laser diodes with a threshold current density of 1.8 kA/cm2 can be pulsed operating up to 340 K. The characteristic temperature To is 125 K and 90 K in the operating temperature ranges 170-220 K and 230-340 K, resDectivelv. The emission spectrum shows a multiple longitudinal mode.