Temperature dependent lasing characteristics of InAs/InP(100) quantum dot laser

We report on the lasing characteristics of InAs/InP(100) quantum dots laser through changing the temperature under continuous-wave mode. Three lasing peaks are simultaneously observed at temperature of 80 K and the lasing order of each peak is unrelated with each other when injection current increases. Laser spectra obtained under fixed current for different temperatures show a drastic influence on their shape. A large spectral broadening is observed at low temperature, while the width of lasing spectra gradually narrows when the operating temperature increased. The lasing process of quantum dot laser is obviously different from that of a reference quantum well laser in the same wavelength region. In addition, very high wavelength stability of 0.088 nm/K in the temperature range of 80–300 K is obtained, which is 6.2 times better than that of reference quantum well laser.     

MOCVD生长带有MQB的量子阱激光器材料

用ＭＯＣＶＤ生长发射波长为８０８ｎｍ的ＡＬＧａＡｓ／ＧａＡｓ量子阱激光器材料。通过在激光器材料的波导中加入多量子势垒（ＭＱＢ）层，有效地限制电子在阱内的复合以及高能电子溢出阱外，从而降低了激光器的阈值电流，提高了它的特征温度。增加了ＭＱＢ后，器件的阈值电流密度Ｉ＿（ｔｈ）从原来的４００～６００Ａ／ｃｍ￣２下降到３００～４００Ａ／ｃｍ￣２，特征温度从１６０Ｋ提高到２１０Ｋ。     

Effect of barrier width on performance of long wavelengthGaInAs/InP multi-quantum-well lasers

It is demonstrated that lasing thresholds in GaInAs/InP MQW lasers under electrical injection are sensitive to the InP barrier thickness and that reducing the barrier width contributes significantly to achieving low-threshold, room temperature operation. In contrast, lasing thresholds under optical pumping show a relative insensitivity to the barrier width. The authors show that this behaviour is consistent with preferential hole capture in the leading wells     

Effects of spontaneous emission rates on lasing characteristics of long-wavelength (1.3 µm) GaAs-based quantum dot lasers

Data are presented characterizing the spectral emission and electroluminescence efficiency dependence on temperature of InGaAs/GaAs quantum dots that result in 1.3 μm lasing at room temperature. Efficient ground state emission is achieved at 80K, but the spontaneous efficiency decreases with increasing temperatures. The ground state spectral width is 26 meV at 80K and 31 meV at 300K. Ground state lasing is obtained over a wide range of temperatures, with an ultralow threshold current density of 14 A/cm² obtained at 80K.     

Room-temperature operation of InP-based InAs quantum dot laser

A ridge waveguide quantum dot (QD) laser with a stripe width of 15 /spl mu/m was fabricated by using the seven-stacked InAs QD layers based on the InAlGaAs-InAlAs material system on InP [001] substrate. Room-temperature lasing operation was observed at 1.501 /spl mu/m, which is the first observation from the InAs QDs with the InAlGaAs-InAlAs structure. The characteristic temperature of the InAs QD laser calculated from the temperature dependence of threshold current density was 135 K in the temperature range from 200 K to room temperature.     

Experimental investigation of the temperature dependence of InAs-AlSb-GaSb Resonant Interband tunnel diodes

The temperature dependence of the current-voltage (I-V) characteristics of InAs-AlSb-GaSb resonant interband tunnel diodes (RITDs) has been investigated from 223 to 423 K. Several device structures were examined, with tunnel barrier thicknesses from 0.6 to 2.0 nm. For all barrier thicknesses, the peak current density (J/sub p/) decreases slightly as the temperature is increased, while the valley current density (J/sub v/) increases with temperature. We found that the temperature rate of change for the peak current density with temperature (/spl part/J/sub p///spl part/T) is nearly independent of barrier thickness, while J/sub v/ increases more rapidly for devices with thicker barriers. In addition, the peak voltage (V/sub p/) was found to be independent of temperature, regardless of barrier thickness. However, the valley voltage (V/sub v/) was observed to decrease with increasing temperature, with more rapid changes observed for RITDs with thicker barriers. Comparison of the temperature performance of RITDs with different barrier thicknesses shows that devices with thinner barriers have I-V characteristics that are less sensitive to temperature, as well as having larger peak and valley current density and voltage for the temperature range from 223 to 423 K. To our knowledge, this is the first report of the temperature dependence of the device characteristics of Sb-based RITDs as a function of barrier width.     

Influence of inhomogeneous broadening and deliberately introduced disorder on the width of the lasing spectrum of a quantum dot laser

Analytical expressions for the shape and width of the lasing spectra of a quantum-dot (QD) laser in the case of a small (in comparison with the spectrum width) homogeneous broadening of the QD energy levels have been obtained. It is shown that the dependence of the lasing spectrum width on the output power at room temperature is determined by two dimensionless parameters: the width of QD distribution over the optical-transition energy, normalized to temperature, and the ratio of the optical loss to the maximum gain. The optimal dimensions of the laser active region have been found to obtain a specified width of the emission spectrum at a minimum pump current. The possibility of using multilayer structures with QDs to increase the lasing spectrum’s width has been analyzed. It is shown that the use of several arrays of QDs with deliberately variable optical-transition energies leads to broadening of the lasing spectra; some numerical estimates are presented.     

InAsSb/InAsSbP double-heterostructure lasers emitting at 3–4 µm: Part I

Previous publications concerned with the development and investigation of InAsSb/InAsSbP double heterostructure lasers emitting at 3–4 μm fabricated by liquid phase epitaxy are reviewed. In pulsed mode, the maximum operating temperature of the lasers is 203 K, the characteristic temperature is 35 K, and differential quantum efficiency is 20±5% at 77K. Mesa-stripe lasers with a 10-to 30-μm stripe width and a 200-to 500-μm cavity length can operate in CW mode up to 110 K. The total optical output power of more than 10 mW at λ=3.6 μm is obtained at T=82 K in CW mode. The output power per mode does not exceed 2 mW/facet. A single-mode lasing is achieved in the temperature range of 12–90 K. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 34, No. 11, 2000, pp. 1396–1403. Original Russian Text Copyright ? 2000 by Danilova, Imenkov, Sherstnev, Yakovlev.     

分子束外延InAlSb红外探测器光电性能的温度效应

采用分子束外延生长方法在InSb （100）衬底上生长p+-p+-n-n+势垒型结构的In1-xAlxSb外延层。运用X射线衍射对材料的晶体质量及Al组分进行测试和表征,InAlSb外延层的半峰宽为0.05,表明外延材料的单晶性能良好,并通过布拉格方程和维戈定律计算出Al组分为2.5%。然后将外延材料制备成多元红外探测并测得77~210 K下的光谱响应曲线,实验发现探测器的截止波长从77 K时的4.48 m增加至210 K时的4.95 m。通过数据拟合得出In0.975Al0.025Sb禁带宽度的Varshni关系式以及其参数Eg（0）、和的值分别为0.238 6 eV,2.8710-4 eV/K,166.9 K。经I-V测试发现,在110 K,-0.1 V偏压下,器件的暗电流密度低至1.0910-5 A/cm-2,阻抗为1.40104 cm2,相当于77 K下InSb探测器的性能。同时分析了温度对器件不同类型的暗电流的影响程度,并得到器件的扩散电流与产生-复合电流的转变温度约为120 K。     

低阈值连续波工作的2.9 THz量子级联激光器

为了获得低阈值连续波工作太赫兹源,采用固源分子束外延技术生长了GaAs/AlGaAs束缚态向连续态跃迁的太赫兹量子级联激光器(QCL)有源区,基于半绝缘-等离子体波导工艺制作了太赫兹量子级联激光器。获得了激光器(腔面未镀高反射膜)的发射光谱和相应的输出特性等性能,其中器件在10 K工作温度、350 mA激励电流下的中心频率为2.93 THz,连续波工作模式的阈值电流密度为156 A/cm2,器件的最大光输出功率为7.84 mW,最高工作温度为62 K。     

Material Growth and Device Fabrication of GaN-Based Blue-Violet Laser Diodes

Studies on first GaN-based blue-violet laser diodes(LDs) in China mainland are reported.High quality GaN materials as well as GaN-based quantum wells laser structures are grown by metal-organic chemical vapor deposition method.The X-ray double-crystal diffraction rocking curve measurements show the fullwidth half maximum of 180″ and 185″ for (0002) symmetric reflection and (10-12) skew reflection,respectively.A room temperature mobility of 850cm2/(V·s) is obtained for a 3μm thick GaN film.Gain guided and ridge geometry waveguide laser diodes are fabricated with cleaved facet mirrors at room temperature under pulse current injection.The lasing wavelength is 405.9nm.A threshold current density of 5kA/cm2 and an output light power over 100mW are obtained for ridge geometry waveguide laser diodes.     

Ridge-width dependence on high-temperature continuous-wave quantum-cascade laser operation

We report continuous-wave (CW) operation of quantum-cascade lasers (/spl lambda/=6 /spl mu/m) up to a temperature of 313 K (40/spl deg/C). The maximum CW optical output powers range from 212 mW at 288 K to 22 mW at 313 K and are achieved with threshold current densities of 2.21 and 3.11 kA/cm/sup 2/, respectively, for a high-reflectivity-coated 12-/spl mu/m-wide and 2-mm-long laser. At room temperature (298 K), the power output is 145 mW at 0.87 A, corresponding to a power conversion efficiency of 1.68%. The maximum CW operating temperature of double-channel ridge waveguide lasers mounted epilayer-up on copper heatsinks is analyzed in terms of the ridge width, which is varied between 12 and 40 /spl mu/m. A clear trend of improved performance is observed as the ridge narrows.     

Room temperature performance of low threshold 1.34-1.44-/spl mu/m GaInNAs-GaAs quantum-well lasers grown by molecular beam epitaxy

Room temperature lasing emission at 1.338 and 1.435 /spl mu/m with threshold current densities of 1518 and 1755 A/cm/sup 2/, respectively, is obtained in broad area GaInNAs-GaAs laser diodes (LDs) grown by molecular beam epitaxy. The 1.338-/spl mu/m LDs show a power output per facet up to 0.20 W/A, a characteristic temperature (T/sub 0/) of 78 K, and an external transparency current density (J/sub tr/) of 0.77 kA/cm/sup 2/. Increasing the lasing wavelength to 1.435 /spl mu/m results in a larger J/sub tr/ of 1.16 kA/cm/sup 2/ and a lower T/sub 0/ of 62 K, due to larger nonradiative recombination. However, the 1.435-/spl mu/m LDs still display a power output per facet up to 0.15 W/A, and a high internal quantum efficiency of 52%. These improved performances are achieved without the need to use strain compensation layers, Sb as a surfactant during the quantum-well growth, or a postgrowth thermal anneal cycle.     

高功率高可靠性9XX nm激光二极管

为了提高半导体激光二极管的输出功率和可靠性,通过在有源区两侧势垒层和波导层之间引入高禁带宽度的GaAsP,抑制有源区载流子的泄漏,极大地改善了器件的性能。研究结果表明:在10~40℃温度范围内器件特征温度从原来的150 K提高至197.37 K(-75.76℃),峰值波长随温度的漂移系数为0.207 nm/℃;条宽200μm、腔长2000μm的9XX nm激光二极管可靠性工作的最大输出功率高达14.4 W;器件在注入电流为7 A时取得71.8%的最大电光转换效率,斜率效率为1.21 W/A。器件在恒定电流下的加速老化测试显示激光二极管可靠性工作寿命达2000 h以上。     

BiFeO3薄膜中的电学输运性质

报道了铁酸铋薄膜样品在80K~300K温度范围直流电学输运性质的研究结果.利用同一前驱体不同老化时间,用化学溶液沉积法在钛酸锶衬底上制备出两种样品.在低阻样品中,低场下电流随电压变化遵从欧姆定律,电阻不随温度变化;而在中等强度外场下显示出肖特基二极管性质.在高阻样品中,低场下电流密度沿晶界分布,输运中的势垒能级为0.57eV;高场下电流的传输则遵从Frenkel-Poole模型,相关势垒能级0.12eV.低阻和高阻两种样品在85K温度下可测最大剩余极化分别为2.6μC/cm2和28.8μC/cm2.     

测量激光器结温的脉冲注入法研究

提出了一种精确测量半导体激光器结温的方法。由于激光器的热容很小，因此采用脉冲注入的方法可以显著减小激光器的温升。研究了脉冲电流注入下激光器的激射波长随环境温度的变化规律，通过实验研究得到电流脉冲宽度和周期与激射波长的关系，理论分析得到的定量关系式与实验结果十分吻合。在此基础上得到了精确测量激光器结温的最佳脉冲参数。即脉宽为10ns，脉冲周期为10μs。并且确定了激光器结温与激射波长的定量关系式，波长随温度的漂移系数为0．0728nm／K。这种方法避免了电学测量法中的结电压波形过冲。测量精度明显优于后者，同时也可以方便地测量封装好的激光器组件的温度特性。     

Temperature dependence of lasing characteristics forlong-wavelength (1.3-μm) GaAs-based quantum-dot lasers

Data are presented on the temperature dependence of 1.3-μm wavelength quantum-dot (QD) lasers. A low-threshold current density of 90 A/cm² is achieved at room temperature using high reflectivity coatings. Despite the low-threshold current density, lasing at the higher temperatures is limited by nonradiative recombination with a rapid increase in threshold current occurring above ~225 K. Our results suggest that very low threshold current density (⩽20 A/cm ²) can be achieved at room temperature from 1.3-μm QD lasers, once nonradiative recombination is eliminated     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Cryogenic performance of double-fused 1.5-μm vertical cavitylasers

The low-temperature performance of vertical cavity lasers (VCL's) is of interest for high-speed data transmission from superconducting and cryogenic semiconductor circuits. Our double-fused 1.5 μm lasers employ a strain-compensated InGaAsP-InP multiquantum-well (MQW) active region that is sandwiched between two AlGaAs-GaAs distributed Bragg reflectors. Continuous wave (CW) lasing at ambient temperature as low as 7 K is measured on the same type of top-emitting devices that previously lased at a record-high temperature of 337 K. The optimum temperature is found at 180 K giving minimum threshold current, maximum modulation bandwidth of 5 GHz, and more than 3 GHz/mA^1/2 modulation current efficiency. The optimum temperature agrees very well with the theoretical prediction. Further device optimization for cryogenic high-speed applications is discussed in detail     

Lasing at a wavelength close to 1.3 µm in InAs quantum-dot structures

The feasibility of lasing at a wavelength close to 1.3 μm is demonstrated in InAs quantum-dot structures placed in an external InGaAs/GaAs quantum well. It is shown that the required wavelength can be attained with the proper choice of thickness of the InAs layer deposited to form an array of three-dimensional islands and with a proper choice of mole fraction of InAs in the InGaAs quantum well. Since the gain attained in the ground state is insufficient, lasing is implemented through excited states in the temperature interval from 85 K to 300 K in a structure based on a single layer of quantum dots. The maximum attainable gain in the laser structure can be raised by using three rows of quantum dots, and this configuration, in turn, leads to low-threshold (70 A/cm²) lasing through the ground state at a wavelength of 1.26 μm at room temperature. Fiz. Tekh. Poluprovodn. 33, 1020–1023 (August 1999)