中红外半导体激光器合束技术研究进展(特邀)

中红外半导体激光器体积小、效率高,在环境检测、空间通讯及军事国防等领域具有重要的应用前景。但是中红外半导体激光器单元器件输出功率低,限制了其在以上领域的应用。激光合束技术是能够实现中红外半导体激光器功率提升的重要途径。文中详细介绍了几种用于中红外半导体激光器的合束方法及中红外半导体激光器合束方面的最新进展。     

红外探测器件的发展

红外辐射探测器已有一百多年的发展史，近代发展尤为迅速．1）红外探测器分做热敏和光电两大门类热敏型探测器有经典的温差热电偶和气动的高雷管属，此外还有热敏电阻．热敏电阻可以用金属、超导体、半导体、金属氧化物半导体、铁电半导体等固体材料制成．其中用氧化铝等陶瓷器件性能稳定，价格低廉；碳和半导体锗、硅及超导测辐射热计的探测率高，响应速度快，但只能在深低温下工作．利用三甘氨酸硫酸盐等铁电晶体的宏观自发极化现象制成的热释电红外探测器室温工作，又有较高的探测率和响应速度，使用很广．光电器件有所谓"外光电"和"内光…     

优质InAsSb/GaAs材料的MBE生长

研究了InAsSb/GaAs材料生长过程中,各种参数对材料质量的影响。优化了生长参数,获得了优质的InAsSb/GaAs材料。采用x射线双晶衍射、红外透射、霍耳测量等手段研究了材料的性能,并制作了光导红外探测器,探测率D可达3×10~9cmHz~(1/2)。W~(-1)。     

980nm高功率列阵半导体激光器

分析了影响列阵半导体激光器输出功率的因素。利用分子束外延生长方法生长出InGaAs/GaAs应变量子阱激光器材料。利用该材料制作出的应变量子阱列阵半导体激光器准连续（100Hz,100μs）输出功率达到80W（室温）,峰值波长为978－981nm。     

940nm列阵窗口半导体激光器

本文分析了影响列阵半导体激光器输出功率的因素。利用分子束外延生长方法生长出InGaAs/GaAs应变量子阱激光器材料。利用该材料制作出的应变量子阱列阵窗口半导体激光器,准连续（500μs,100Hz）输出功率达到80W（室温）,峰值波长为939－941nm。     

InAs基中红外带间级联激光器中的自加热效应

制备并测试了II型中红外带间级联激光器,制备的器件在脉冲和连作模式下最高工作温度分别为275 K和226 K。80 K下器件激射波长为3.8 μm左右,阈值电流密度约17 A/cm²。对器件在连续工作模式下的自加热效应进行了分析,并利用有限元方法模拟了器件连续工作时的温度分布图。分析和模拟结果均表明自加热效应是限制器件连续工作温度的重要因素,进一步提升散热性能将是进一步提升器件工作温度的有效手段。     

面向工程化应用的量子阱红外探测材料制备研究

为了得到高性能的量子阱红外探测材料,本文通过建立系统的材料设计、材料生长及材料表征体系,对面向工程化应用要求的单色以及双色红外探测的量子阱材料制备技术进行了较深入探索,并得到了相应部分器件的测试结果,实践证明,通过工艺与控制过程优化,量子阱红外探测材料的制备可实现高的可控性和稳定性。     

VSWIR to VLWIR MBE grown HgCdTe material and detectors for remote sensing applications

The molecular beam epitaxy (MBE) growth technology is inherently flexible in its ability to change the Hg_1−xCd_xTe material’s bandgap within a growth run and from growth run to growth run. This bandgap engineering flexibility permits tailoring the device architecture to the various specific requirements. Material with active layer x values ranging from ∼0.198 to 0.570 have been grown and processed into detectors. This wide range in x values is perfectly suited for remote sensing applications, specifically the National Polar Orbiting Environmental Satellite System (NPOESS) program that requires imaging in a multitude of infrared spectral bands, ranging from the 1.58 to 1.64 μm VSWIR (very short wave infrared) band to the 11.5 to 12.5 μm LWIR (longwave infrared) band and beyond. These diverse spectral bands require high performance detectors, operating at two temperatures; detectors for the VSWIR band operate near room temperature while the SWIR, MWIR (mid wave infra red), LWIR and VLWIR (very long wave infrared) detectors operate near 100K, because of constraints imposed by the cooler for the NPOESS program. This paper uses material parameters to calculate theoretical detector performance for a range of x values. This theoretical detector performance is compared with median measured detector optical and electrical data. Measured detector optical and electrical data, combined with noise model estimates of ROIC performance are used to calculate signal to noise ratio (SNR), for each spectral band. The SNR are compared with respect to the meteorological NPOESS system derived focal plane. The derived system focal plane requirements for NPOESS are met in all the spectral bands.     

（英）利用分子束外延在GaAs基上生长高特征温度的InAs量子点激光器

通过MBE外延系统生长了1.3 μm的GaAs基InAs量子点激光器.为了获得更好的器件性能,InAs量子点的最优生长温度被标定为520 ℃,并且在有源区中引入Be掺杂.制备了脊宽100 μm,腔长2 mm的激光器单管器件,在未镀膜的情况下,达到了峰值功率1.008 W的室温连续工作,阈值电流密度为110 A/cm^-2,在80℃下仍然可以实现连续工作,在50 ℃以下范围内,特征温度达到405 K.     

The growth of GaAs,AIGaAs, InP and InGaAs by chemical beam epitaxy using group III and V alkyls

The growth kinetics of chemical beam epitaxy (CBE) were investigated with the growth of GaAs, AIGaAs, InP, and InGaAs. Results obtained with epilayers grown by using trimethylarsine (TMAs) and triethylphosphine (TEP) instead of arsine (AsH3) and phosphine (PH₃) were reviewed with some additional results. The CBE grown epilayers have similar optical quality to those grown by molecular beam epitaxy (MBE). Superlattices of GaAs/AlGaAs with abrupt interfaces have been prepared. Since trimethylindium (TMIn) and triethylgallium (TEGa) used in the growth of InGaAs emerged as a single mixed beam, spatial composition uniformity was automatically achieved without the need of substrate rotation in the InGaAs epilayers grown. Lattice-mismatch Δα/α< 1 x 10^-3 have been reproducibly obtained. For epilayers grown with high purity TMAs source, room-temperature electron mobility as high as 9000 cm²/V sec and concentrations of ˜7 x 10¹⁵ cm^-3 were produced. In general, the electron mobilities were as good as those obtained from low-pressure metalorganic chemical vapor deposition. (MO-CVD). Unlike MBE, since the In and Ga were derived by the pyrolysis of TMIn and TEGa molecules at the heated substrate surface, respectively, oval defects observed in MBE grown epilayers due to Ga splitting from Ga melt were not present in CBE grown epilayers. This is important for integrated circuit applications. Unlike MO-CVD, the beam nature of CBE allows for selective area growth of epilayers with well-defined smooth edges using mask shadowing techniques. Typically, growth rates of 2-5μm/h for InP, 2-6μm/h for GaAs and AIGaAs, and 2-5μm/h for InGaAs were used.     

Growth of the dilute magnetic semiconductor GaMnN by molecular-beam epitaxy

Growth by molecular-beam epitaxy (MBE) of the dilute-magnetic alloy GaMnN is reported. The Mn concentration, as determined by Auger electron spectroscopy (AES), is found to be linear with increasing Mn-cell temperature up to ∼43at.%Mn. No second phases are observed for Mn levels below 9 at.%. The cubic-phase Mn₄N is found to be the thermodynamically stable phase at the growth conditions used to produce GaMnN. Hysteresis in M versus H is observed in both GaMnN and GaMnN:C grown on both sapphire and metal-oxide chemical-vapor deposition (MOCVD) GaN at several growth temperatures. Magnetotransport results show the anomalous Hall effect, negative magnetoresistance, and magnetic hysteresis, indicating that Mn is incorporating into the GaN and forming the ferromagnetic-semiconductor GaMNN. Room-temperature hysteresis is obtained in magnetization measurements with an optimum Mn concentration of ∼3 at.%.     

In-situ process for AlGaAs compound semiconductor: Materials science and device fabrication

Processing of III-V compound semiconductor devices in an ultra-high vacuum or a controlled environment has received much attention during the past few years. Major advantages ofn- situ processing include the preservation of pristine material surface, improved device performance, and fabrication of novel devices. This paper reviews anin- situ process compatible with molecular beam epitaxy (MBE) with emphasis on the removal of oxides and surface contaminants from air-exposed GaAs and AIGaAs. We have characterized deep-etched and MBE regrown AIGaAs with the etching achieved using electron cyclotron resonance plasma treatment. A buried heterostructure vertical-cavity surface emitting laser diode fabricated using thisin- situ process is presented.     

半导体激光器的输出光强-电流曲线与阈值

半导体激光器的受激发射光谱和输出光功率(P)-电流(I)特性曲线都是表征其性能的重要数据。它们也是确定半导体激光器受激发射阈值电流(I_(th))的常规测量方法。但是发射光谱是给定工作电流(I)时测量的,必须尽可能多次测量不同I值时的发射光谱,同时仔细区别超辐射和受激发射光谱才能确定I_(th)值;而从P-I曲线的转折点或外推P-I曲线到P=0     

中红外量子级联激光器的发射光谱测量

基于FTIR光谱仪建立了中红外半导体激光器发射光谱测量系统,并引入双调制技术改善了系统的性能。用此系统对中红外波段量子级联激光器的激射特性进行了测量,对有关测量结果进行了分析,并对系统应用中的有关问题进行了讨论。     

940 nm高功率半导体激光器研究

报道了一种采用大光学腔结构的InGaAs/GaAs/AlGaAs应变量子阱高功率半导体激光器。在量子阱能级本征值方程的数值求解基础上 ,优化了InGaAs阱层材料的In组份含量 ;采用大光学腔结构以有效降低垂直于结平面方向的光束发散角及腔面的光功率密度 ,实现器件的高功率、低发散角光。设计的激光器外延结构采用分子束外延 (MBE)方法生长 ,成功获得具有较低激射阈值的 94 0nm波长激光器外延片。对 10 0 μm条形 ,10 0 0 μm腔长的制备器件测试表明 ,器件的最大连续输出功率达到 2W ,峰值波长为 939.4nm ,远场水平发散角为 10° ,垂直发散角为 30°。器件的阈值电流为 30 0mA。     

Enhanced magnetic anisotropy and high hole mobility in magnetic semiconductor Ga1-x-yFexNiySb

(Ga,Fe)Sb is a promising magnetic semiconductor (MS) for spintronic applications because its Curie temperature (T_C) is above 300 K when the Fe concentration is higher than 20%. However, the anisotropy constant K_u of (Ga,Fe)Sb is below 7.6 × 10³ erg/cm³ when Fe concentration is lower than 30%, which is one order of magnitude lower than that of (Ga,Mn)As. To address this issue, we grew Ga_1-x-yFe_xNi_ySb films with almost the same x (≈24%) and different y to characterize their magnetic and electrical transport properties. We found that the magnetic anisotropy of Ga_0.76-yFe_0.24Ni_ySb can be enhanced by increasing y, in which K_u is negligible at y = 1.7% but increases to 3.8 × 10⁵ erg/cm³ at y = 6.1% (T_C = 354 K). In addition, the hole mobility (µ) of Ga_1-x-yFe_xNi_ySb reaches 31.3 cm²/(V∙s) at x = 23.7%, y = 1.7% (T_C = 319 K), which is much higher than the mobility of Ga_1-xFe_xSb at x = 25.2% (µ = 6.2 cm²/(V∙s)). Our results provide useful information for enhancing the magnetic anisotropy and hole mobility of (Ga,Fe)Sb by using Ni co-doping.     

低温退火对稀磁半导体(Ga,Mn)As性质的影响

利用低温分子束外延技术在GaAs(001)上外延生长出厚度为500nm的稀磁半导体(Ga,Mn)As薄膜. 双晶X射线衍射证明其为闪锌矿结构，晶格参数为0.5683nm，据此推导出其Mn含量为7%. 磁测量结果揭示其铁磁转变温度为65K. 观察了低温退火处理对(Ga,Mn)As磁性质的影响，发现生长后退火处理显著提高了其铁磁转变温度，可以达到115K.