Optimizing back surface field for improving Voc of(Al)GaInP solar cell

GaInP and AlGaInP solar cells were grown by metal organic chemical vapor deposition (MOCVD), and theoretical analysis demonstrated that hetero-interface recombination velocity plays an important role in the optimizing of cell performance, especially the interface between base layer and back surface field (BSF). Measurements including lattice-matched growth and pseudo-BSF were taken to optimize BSF design. Significant improvement of V_oc in GaInP and AlGaInP solar cells imply that the measures we took are effective and promising for performance improvement in the next generation high efficiency solar cells.     

Si掺杂的AlGaInP/GaInP多量子阱光学特性

低压MOCVD方法生长了掺Si与不掺Si的AlGaInP/GaInP多量子阱结构,运用X射线双晶衍射与光荧光技术研究了掺Si对量子阱性能的影响.测试结果表明掺Si使量子阱的生长速度增加,掺Si量子阱的光荧光强度比未掺Si量子阱的光荧光强度改善了一个数量级.     

High-performance 670-nm AlGaInP/GaInP visible strained quantum welllasers

We have grown high-performance AlGaInP/GaInP visible (670 mn) strained quantum well lasers by low-pressure metalorganic chemical vapor deposition. With AlInP cladding layer, a high-power AlGaInP/GaInP visible laser diode is achieved. Its threshold current is about 30 mA. The output power of this laser diode can maintain, at least, at 32 mW under continuous-wave (CW) operation at room temperature. High slope efficiency (0.8 mW/mA) and differential quantum efficiency (0.87) can be achieved. To improve beam quality, AlGaInP/GaInP visible lasers with and without depressed index cladding layer are theoretically and experimentally studied. From experimental results, the transverse beam divergence can be reduced from 41.4° to 26.2° while maintaining a low threshold current (from 36 mA to 46 mA). By using the transfer matrix method, our theoretical calculations are in good agreement with the experimental results     

垒层Si掺杂对AIGaInP/GaInP多量子阱性能的影响

低压MOCVD方法生长了垒层掺Si与不掺Si的AlGaInP/GaInP多量子阱结构,运用X双晶衍射与光荧光技术研究了掺Si对量子阱性能的影响.测试结果表明垒层掺Si使量子阱的生长速度增加,掺Si量子阱的光荧光强度比未掺Si量子阱的光荧光强度增强了1 3倍.     

(Al)GaInP laser with lateral confinement by epitaxial growth onnonplanar substrates

The authors present an AlGaInP/GaInP strained QW laser with AlGaAs cladding layers grown over nonplanar substrates. Excellent device quality and performance is obtained on substrates patterned with ridges prior to epitaxial growth. The lateral current and carrier confinement achieved by exploiting the disordering of the neutral superlattice at ridge sidewalls with shallow angles results in a threshold current density for 5-μm-wide stripes that is one-half that of conventional devices. The potential of this device for high electrical-to-optical conversion makes it well suited for applications to dense addressable laser arrays     

Aging characteristics of AlGaInP/GaInP visible-light lasers (?L = 678 nm)

An aging test for AlGaInP/GaInP visible-light lasers (?L = 678 nm) with 3?5 mW lasing output power was carried out for over 2000 h at room temperature. Significant degradation has not been observed during this test. The results indicate that the AlGaInP laser diodes have a considerable lifetime, suitable for practical use.     

Fabrication and operation of first-order GaInP/AlGaInP DFB lasersat room temperature

The fabrication and operation properties of first-order distributed-feedback (DFB) GaInP/AlGaInP double quantum well lasers are reported. The lasers with DFB grating periods between 106 and 109 nm show stable single-mode operation in the visible range from 694.0 to 709.5 nm at room temperature     

GaInP/AlGaInP index waveguide-type visible laser diodes with dry-etched mesa stripes

GaInP/AlGaInP index waveguide-type visible-light laser diodes with dry-etched mesa stripes have been fabricated by Cl/sub 2/ reactive ion beam etching for the first time. The AlGaInP cladding layer, which is normally very difficult to dry etch due to problems with Al oxidation and the low volatility of In and its reaction products, was etched smoothly with high depth accuracy. The etched mesa stripes were buried by metal organic vapour-phase epitaxy without crystal discontinuity at the regrown surface. The threshold current under room-temperature pulsed operation is 35 mA (L=300 mu m), which is almost the same value as that for wet-etched lasers.<>     

High performance of AlGaInP/GaInP visible lasers by strain induced effects

An AlGaInP/GaInP visible strained single quantum well (SSQW) laser has been investigated. In comparison with a conventional lattice-matched single quantum well (SQW) laser, it was found that a 25% increase in the differential gain coefficient beta and 60% decrease in the transparency current density J/sub 0/ have been obtained by incorporating 0.65% compressive SSQW active layer structure.<>     

GaInP/AlGaInP脊形波导激光器器件结构的优化研究

通过优化脊形波导的结构参数可以降低脊形波导激光器的阈值电流,提出了实现亚微米脊宽,从而降低阈值电流的方法。针对脊形波导制作过程中蚀刻深度不易控制的问题,对GaInP/AlGaInP材料中加入蚀刻阻挡层进行了研究。     

GaInP/AlGaInP应变多量子阱激光器垂直于结方向上的光束质量研究

用转移矩阵方法对 680nmGaInP/AlGaInP应变多量子阱激光器的波导模式作了分析和计算。根据非傍轴光束传输的矢量矩理论 ,对该激光器垂直于结平面方向上的光束质量因子M2 ⊥ 进行了理论计算 ,结果表明M2 ⊥ 小于 1,和实验结果相符合。这一结果有助于认识半导体激光器垂直于结方向上光束的内在本性     

MOCVD GaInAsP/GaInP/AlGaInP laser structures emitting at 780 nm

Metal-organic chemical vapor deposition (MOCVD) was used to form laser heterostructures in the system of GaInAsP/GaInP/AlGaInP solid solutions. The design of the laser structure was chosen on the basis of the calculated band offsets at the heteroboundaries in the active region of the waveguide. A maximal optical power of 320 mW is attained at the output of the mesa-stripe diode laser with a stripe width of W=5 µm in continuous-wave mode at 780 nm.     

Investigation of TE and TM polarised laser emission in GaInP/AlGaInP lasers by growth-controlled strain

GaInP/AlGaInP double heterostructure lasers can be obtained with either TE or TM polarised emission. In addition it it shown that, by using appropriate samples, TE or TM lasing can be selected by changing the temperature or the cavity length.<>     

Computer simulation of an operation of the GaInP/AlGaInP QW VCSELs: Excitation of various transverse LPij modes

A comprehensive fully self-consistent optical–electrical–thermal-recombination model of the 650-nm oxide-confined GaAs-based GaInP/AlGaInP vertical-cavity surface-emitting diode lasers (VCSELs) is used to determine their anticipated room-temperature (RT) continuous-wave (CW) performance characteristics. As expected, for the devices with very large active regions, higher-order transverse LP_ij modes exhibit the lowest lasing thresholds. However, the desired single fundamental LP₀₁ mode operation remains dominating one for relatively large active regions of diameters up to as much as 10 mm. Therefore, the 650-nm GaInP/AlGaInP QW VCSELs have been found to offer a very promising RT CW performance as sources of carrier radiation for the optical communication taking advantage of plastic (polymer) optical fibers (POFs).     

Very low threshold current density of a GaInP/AlGaInP double-heterostructure laser grown by MOCVD

A GaInP/AlGaInP broad-area (60 × 500 ?m2) laser grown by MOCVD has obtained a very low threshold current density Jth of 1.1 kA/cm2. The dependence of Jth and differential quantum efficiency on cavity length was measured to determine internal quantum efficiency, losses and the gain constant, which were found to be comparable to these characteristics in an AlGaAs laser.     

Doping level and type of GaInP saturable absorbing layers forrealizing pulsating 650-nm-band AlGaInP laser diodes

On AlGaInP laser diodes, the doping level and type of GaInP saturable absorbing (SA) layers suitable for self sustained pulsation are clarified. Optical properties of n- and p-type GaInP quantum wells (QWs) have been evaluated by means of time-resolved photoluminescence (TRPL) spectroscopy. As the doping level becomes higher, the recombination lifetime becomes shorter, and it can be reduced to 1.1 ns at our highest doping level (1=2×10¹⁸ cm^-3). For highly doped n-type QW, a PL peak energy shift as large as 26 meV is observed by high-density excitation. Highly doped p-type SA layer is suitable for self-sustained pulsating laser diodes, because it offers short recombination lifetime and no Burstein shift under highly excited condition     

Effect of spin-orbit split-off bands on GaInP/AlGaInP strainedquantum well lasers

We theoretically analyzed the effect of the spin-orbit split-off band on GaInP/AlGaInP strained quantum well lasers using 6×6 Luttinger-Kohn Hamiltonian. Because of the small spin splitting energy of GaInP, we show that the spin-orbit split-off subbands strongly couple with heavy and light hole subbands, and linear gain properties are greatly different from those without the effect of spin-orbit split-off bands. The unstrained quantum well structure is most influenced by the spin-orbit split-off bands, and laser characteristics such as the differential gain and threshold current are degraded. The compressive-strained quantum well has the lowest threshold current, and the tensile-strained quantum well has largest differential gain, which is improved by the effect of the spin-orbit split-off bands     

1.5-W CW S-band GaInP/GaAs/GaInP double heterojunction bipolartransistor

We report the first large-signal power result from a double heterojunction bipolar transistor (DHBT) based on the GaInP/GaAs/GaInP material system. A CW output power of 1.51 W and a power added efficiency of 52% were achieved at 3 GHz. Because the GaInP collector has a relatively high bandgap of 1.89 eV, high DC bias voltage operation with collector bias extending to 20 V (for a 40-V swing) is possible in this GaInP/GaAs/GaInP DHBT. This high DC bias voltage operation represents a unique advantage over the more conventional AlGaAs/GaAs HBT     

GaInAsP/GaInP/AlGaInP MOCVD-grown diode lasers emitting at 808 nm

The MOCVD epitaxy has been used to grow the GaInAsP/GaInP/AlGaInP laser heterostructures with a narrow symmetric waveguide and broad asymmetric waveguide. Mesa stripe 100 μm aperture diode lasers emitting at 808 nm were manufactured. It is shown that a SiO₂/Si dielectric mirror coating of Fabry-Perot faces of Al-free semiconductor lasers does not result in catastrophic optical mirror damage. It is found that the maximum optical output power of Al-free diode lasers is limited by catastrophic optical damage of the laser heterostructure. Maximum values of optical output power of 5.1 and 9.9 W have been attained in diode lasers with a narrow symmetric waveguide and broad asymmetric waveguide, respectively.