Effects of Lateral Diffusion on the Temperature Sensitivity of the Threshold Current for 1.3-$mu{hbox {m}}$ Double Quantum-Well GaInNAs–GaAs Lasers

We present an experimental and theoretical investigation of the temperature dependence of the threshold current for double quantum well GaInNAs-GaAs lasers in the temperature range 10 degC-110 degC. Pulsed measurements of the threshold current have been performed on broad and narrow ridge wave guide (RWG) lasers. The narrow RWG lasers exhibit high characteristic temperatures (T₀) of 200 K up to a critical temperature (T_c), above which T₀ is reduced by approximately a factor of 2. The T0-values for broad RWG lasers are significantly lower than those for the narrow RWG lasers, with characteristic temperatures on the order of 100 (60) K below (above) T_c. Numerical simulations, using a model that accounts for lateral diffusion effects, show good agreement with experimental data and reveal that a weakly temperature dependent lateral diffusion current dominates the threshold current for narrow RWG lasers.     

A temperature-dependent DC model for quarter-micron LDD pMOSFET'soperating in a Bi-MOS structure

A temperature-dependent analytical model for deep submicrometer LDD p-channel devices operating in a Bi-MOS structure is reported for the first time. This model is based on experimental data obtained from 0.25-μm process wafers with a wide range of technologies (0.25-1.0 μm). The measurements have been performed within the temperature range 223-398 K (-50°C to +125°C). The model accounts for the effects of independently biasing the source, drain, gate and body potentials, scaling, and the influence of temperature on the threshold voltage and the device currents. The effect of temperature on the device transconductance and the output conductance have also been examined. The results revealed that close agreement between the analytical model and the experimental has been achieved. Comparisons between the principal MOS current and the lateral bipolar current have been made to demonstrate the improvement of the latter with temperature for the quarter-micron devices     

Continuous-wave operation of terahertz quantum-cascade lasers

We report continuous-wave (CW) operation of a 4.4-THz quantum-cascade laser grown in the GaAs-AlGaAs materials system by molecular beam epitaxy. The device operates at 4 K with a threshold current of 160 mA, and an output power of /spl sim/25 /spl mu/W. In pulsed mode, the maximum operating temperature is 52 K, with a threshold current of 108 mA at 4 K. CW lasing was achieved by using a small cavity ridge area (60/spl times/600 /spl mu/m), and by coating one of the laser facets. These two features allowed for a substantial decrease of the threshold current and therefore reduced detrimental heating effects. The role played by the lateral resistance of the 800-nm GaAs layer underneath the active region was also investigated. Experimental data is presented showing that the temperature of the active region, which eventually hinders CW lasing, can be substantially influenced by the value of this lateral resistance.     

Design of quantum well AlGaAs-GaAs stripe lasers for minimizationof threshold current-application to ridge structures

The gain saturation effect and the various leakage currents related to a strip structure (spreading current, lateral diffusion current, optical cavity recombination current, and Auger recombination current) are considered. The minimum threshold current (3.3 mA) is obtained with a multiquantum-well (MQW) structure (5×80 Å) at a cavity length of 80 μm. At these values, the lateral leakage current (spreading and lateral diffusion currents) represents about 50% of the threshold current. It is shown that for short-cavity lasers, the MQW is preferred to the SQW (single-quantum-well) structure. However, the well number in the active layer of a ridge structure is limited by the decrease of the parallel confinement and the increase of the lateral leakage current. Finally, good agreement was obtained in comparing the calculations with experimental results for GRINSCH (graded-index separate-confinement heterojunction) SQW lasers     

脊形InGaN激光器的温度分布及其对器件特性的影响

利用含时二维热传导模型分析了蓝宝石衬底上生长、制作的脊形InGaN激光器内波导层的温度分布和时间演化规律.由于较大的阈值电流和电压以及较差的衬底导热性能,脊形下波导层内会产生较高温升并在脊形内外形成较大的温度台阶.由于脊形波导的弱自建波导特性,这一温度台阶会对侧向模式的限制产生较大的影响.短脉冲工作下的时间分辨L-I测试以及时间分辨远场和光谱测试结果显示,脊形内外的温度台阶会改善波导对高阶模的限制,导致器件的阈值电流下降,斜率效率升高.而有源区的温升又会导致斜率效率的严重下降.     

Temperature Distribution in Ridge Structure InGaN Laser Diodes and Its Influence on Device Characteristics

利用含时二维热传导模型分析了蓝宝石衬底上生长、制作的脊形InGaN激光器内波导层的温度分布和时间演化规律.由于较大的阈值电流和电压以及较差的衬底导热性能,脊形下波导层内会产生较高温升并在脊形内外形成较大的温度台阶.由于脊形波导的弱自建波导特性,这一温度台阶会对侧向模式的限制产生较大的影响.短脉冲工作下的时间分辨L-I测试以及时间分辨远场和光谱测试结果显示,脊形内外的温度台阶会改善波导对高阶模的限制,导致器件的阈值电流下降,斜率效率升高.而有源区的温升又会导致斜率效率的严重下降.     

Characterization of thin p-clad InGaAs single-quantum-well lasers

Low-ridge, thin p-clad InGaAs single-quantum-well (SQW) lasers with shiny Au contacts have been fabricated using a pulsed anodic oxidation technique. Although the ridge is very low (130 nm), the lateral refractive index step is sufficiently large to provide strong lateral waveguiding. Pulsed current measurements of threshold current, operating wavelength, and lateral far field as a function of ridge width are presented and compared with measured values reported for low-ridge and oxide-defined lasers fabricated from conventional thick p-clad material. The CW performance characteristics of five-micron-wide, low-ridge, thin p-clad lasers are shown to be comparable to those of conventional InGaAs SQW high-ridge waveguide lasers     

Large CW power, very-low-threshold, single transverse modeoperation of vertical cavity mushroom structure surface emitting lasers

Summary form only given. Continuous-wave GaAs mushroom structure surface emitting laser (MSEL) operation at a threshold current as low as 1.6 mA, an output power >2.0 mW, and a single transverse mode up to three times threshold current is reported. The relatively large CW output power was achieved by reducing the series resistance using a selective zinc diffusion. The low threshold current and single-mode operation are attributed to good lateral current confinement in a small constricted region formed by mesa undercutting. The complete device was mounted junction-side up on a chip carrier and tested CW at room temperature. Some results are given     

The effect of temperature dependent processes on the performance of1.5-μm compressively strained InGaAs(P) MQW semiconductor diodelasers

We describe measurements of the threshold current I_th and spontaneous emission characteristics of InGaAs (P)-based 1.5-μm compressively strained multiple-quantum-well semiconductor lasers from 90 K to above room temperature. We show that below a break-point temperature, T_B≈130 K, I_th and its temperature dependence are governed by the radiative current. Above this temperature, a thermally activated Auger recombination process becomes the dominant recombination mechanism responsible for both I_th and its temperature sensitivity. At room temperature nonradiative Auger recombination is found to account for approximately 80% of the threshold current in these devices     

Embedded-stripe GaAs-GaAlAs double-heterostructure lasers with polycrystalline GaAsP layers--I: Lasers with cleaved mirrors

We report a new type of embedded stripe laser in which low-order mode CW oscillation is successfully attained at room temperature. In order to achieve lateral current confinement, a high-resistivity polycrystalline GaAsP layer is formed around the mesa stripe by selective vapor-phase growth technology. It turns out that a stable single-mode operation is attained at an injected current up to several times the threshold value.     

AlGaAs/GaAs lateral current injection multiquantum well (LCI-MQW)laser using impurity-induced disordering

A lateral current injection (LCI) multiquantum-well (MQW) laser having planar structure is proposed and its advantages compared with conventional vertical structure lasers. A LCI-MQW laser has been fabricated by using Si- and Zn-induced disordering of an MQW active layer. It is shown that a threshold current of 27 mA is achieved under pulsed current driven at room temperature and a very low stray capacitance of 0.27 pF is obtained at zero bias voltage     

Detector-enclosed vertical-cavity surface emitting lasers

The authors report the use of novel monolithic lateral photodetectors surrounding vertical-cavity surface emitting lasers to determine the radiative transition rate and lasing threshold independent from the axial emission. The lateral detector photocurrent increases with increasing laser drive current, even as the axial emission rolls over and terminates. This clearly establishes that laser output is limited by the detuning between the Fabry-Perot cavity resonance and the gain bandwidth with temperature, rather than the temperature dependence of the gain.<>     

半导体激光器边缘绝热封装改善慢轴光束质量

为了削弱激光器工作时芯片横向温度不均而导致的热透镜效应对慢轴发散角的影响,提高慢轴的光束质量,引入了边缘绝热封装方式,即在激光器芯片两侧与过渡热沉之间加入空气隙,以降低两侧的传导散热。利用有限元分析软件ANSYS 18.0对该封装结构中激光器芯片的温度进行仿真。结果表明:当工作电流为1.6 A,芯片与热沉的接触宽为200μm时,慢轴发散角由普通封装时的11.5°减小至8.2°,降幅为28%,光束参数积和光束质量因子也分别降低了28%和24%,热阻增大了6%。边缘绝热封装对器件激射波长、阈值电流、电光转换效率的影响很小。     

Double quantum wire GaAs/AlGaAs diode lasers grown byorganometallic chemical vapor deposition on grooved substrates

Structure and lasing characteristics of double-quantum-wire lasers are reported. Threshold current as low as 2.4 mA and continuous wave operation at room temperature were achieved for lasers with uncoated facets. Subbands due to lateral quantum confinement were observed in the laser spectra. Good agreement between measured dependence of threshold current on cavity length and a simple model accounting for gain saturation was found     

Localised temperature dynamics of GaAlAs laser facets investigated by Raman microprobe measurements

Raman micro-probe studies of diode laser facet temperatures in CW operation show a significant linear temperature rise below the laser threshold and a rapid nonlinear heating above the threshold. Dynamical measurements using current injection pulses show fast heating of the laser facet with a sub-microsecond risetime and much slower cooling within several micro-seconds.<>     

Comprehensive modeling of diode arrays and broad-area devices withapplications to lateral index tailoring

A numerical model for calculating the emission characteristics of diode laser arrays and broad-area devices operating well above threshold is discussed. This model uses the beam propagation technique for determining the field intensities for several lateral modes, while simultaneously and self-consistently solving for the two-dimensional current flow through the laser structure and the subsequent carrier diffusion in the active region. The active-region temperature distribution is also computed in a self-consistent manner, based on the flow of heat generated in the active region through the layered device structure to a constant-temperature heat sink. The model is applied by investigating the sensitivity of the lasing modes of a broad-area diode laser to variations in the lateral temperature distribution     

Thermal instability in very small p-n junctions

Thermally induced second breakdown is studied in very small 6- to 10-volt silicon diodes having uniform breakdown. The formation of a small high-current density region is observed optically at the onset of thermal breakdown. Incremental resistance measurements can be used to determine nondestructively the threshold current for thermal breakdown. The threshold temperature for thermal breakdown is measured using the avalanche voltage temperature coefficient. The voltage drop associated with thermal breakdown is shown to be due to a sudden change in active area of the junction rather than to melting of the crystal.     

AlInAs氧化物限制1.3μm低阈值边发射激光器

研究制作了一种利用AlInAs氧化物作为限制的1.3μm边发射AlGaInAs多量子阱激光器.有源层上方和下方的AlInAs波导层被氧化作为电流限制层.这种结构提供了良好的侧向电流限制和光场限制.当电流通道为5μm宽时,获得了12.9mA的阈值电流和0.47W/A的斜率效率.与具有相同宽度的脊条的脊波导结构的激光器相比,这种AlInAs氧化物限制的激光器的阈值电流降低了31.7%,斜率效率稍微有所提高.低阈值和高效率的特性表明,氧化AlInAs波导层能够提供良好的侧向电流限制.这种AlInAs氧化物限制的激光器垂直方向的远场半高全宽角为36.1°,而水平方向的是21.6°,表明AlInAs氧化物对侧向光场也有很强的限制能力.     

RF PDSOI LDMOS器件的电离总剂量辐照效应

研制了一种用于射频领域的叉指栅PDSOI LDMOS晶体管,并分析了总剂量辐照对其静态和小信号射频特性的影响.其静态工作模式下的辐照响应由前/背栅阈值、泄漏电流、跨导和输出特性表征,而其交流工作模式下的辐照响应由截止频率和最高振荡频率表征.实验表明,在室温环境下经过总剂量为1Mrad(Si)的γ射线辐照,不同尺寸和结构的射频SOI LDMOS晶体管的各项指标均表现出明显退化,并且仅当器件工作在静态模式时LBBC LDMOS才表现出优于BTS LDMOS的抗辐照性能.     

RF PDSOI LDMOS器件的电离总剂量辐照效应

研制了一种用于射频领域的叉指栅PDSOI LDMOS晶体管,并分析了总剂量辐照对其静态和小信号射频特性的影响. 其静态工作模式下的辐照响应由前/背栅阈值、泄漏电流、跨导和输出特性表征,而其交流工作模式下的辐照响应由截止频率和最高振荡频率表征. 实验表明,在室温环境下经过总剂量为1Mrad(Si)的γ射线辐照,不同尺寸和结构的射频SOI LDMOS晶体管的各项指标均表现出明显退化,并且仅当器件工作在静态模式时LBBC LDMOS才表现出优于BTS LDMOS的抗辐照性能.