Improvement of GaAs/AlGaAs quantum well laser diodes by rapid thermal annealing

Post-growth annealing is shown to improve the laser diode quality of GaAs/AlGaAs graded-index separate confinement heterostructure quantum well laser diode structures grown at a nonoptimal substrate temperature lower than 680°C by molecular beam epitaxy. Reduction by a factor of up to three in the threshold current was accompanied by a reduction in the interface trap density. The reduced threshold current is still higher than that of laser diodes grown at the optimal temperatures which are between 680 and 695°C. The improvement in laser diode performance is ascribed to the reduction of interface nonradiative recombination centers.     

Low threshold current density 1.5 mu m GaInAs/AlGaInAs graded-index separate-confinement-heterostructure quantum well laser diodes grown by metal organic chemical vapour deposition

A low threshold current density of 640 A/cm/sup 2/ was obtained in a 1.5 Gmm GaInAs/AlGaInAs multiple quantum well laser diode, grown by metal organic chemical vapour deposition, with continuously graded-index separate-confinement heterostructure. An internal waveguide loss of 14 cm/sup -1/ and internal quantum efficiency of 59% were obtained, which are comparable to those of GaInAs/GaInAsP quantum well laser diodes.<>     

快速热退火提高应变InAs／InP量子阱结构的晶体质量

研究了快速热退火对应变ＩｎＡｓ／ＩｎＰ单晶子阱结构光学性质的影响。样品经最佳条件７００℃，５ｓ的快速热退火，８Ｋ温度下量子阱的荧光强度地加了４倍，量子阱荧光峰仅蓝移１．５ｍｅＶ。     

Double-heterojunction bipolar transistors in InP/GaInAs grown by metal organic chemical vapour deposition

Double-heterojunction bipolar transistor structures in InP/GaInAs have been grown by low-pressure metal organic chemical vapour deposition. Good control of the Zn dopant in the GaInAs base layer was achieved, and devices with current gains up to 300 at current densities of 1.4kA/cm2 have been demonstrated.     

MOCVD growth of strained multiple quantum well structure for 1.3 μm InAsP/InP laser diodes

In this article, we describe the growth and characterization for 1.3 μm InAsP/InP strained multiple quantum well (SMQW) laser diodes (LDs) with separate confinement heterostructure grown at 580°C by metalorganic chemical vapor deposition. The grown strained single quantum well (SSQW) stack and strained multiple quantum well (SMQW) structures are characterized using double-crystal X-ray diffraction and photoluminescence (PL) to confirm the structural and optical qualities for practical device applications. The InAsP/InP SSQW stack grown at 580°C appears to be extremely abrupt, uniform, free of misfit dislocations and narrow PL half width. Although the InAsP/InP SMQWs grown at 580°C maintain its structural integrity throughout the deposition sequence, the slightly broader PL half width for InAsP/InP SMQW structure is attributed to the dislocations resulted from a large net strain. Laser emission can be achieved by using the InAsP/InP SMQWs and the lasing wavelength is in a good agreement with our designed structure. The experimental data of broad-area and ridge waveguide LDs are described in detail.     

InGaAs/InGaAlAs/InAlAs/InP SCH-MQW laser diodes grown by molecular-beam epitaxy

InGaAs/InGaAlAs/InAlAs/InP separate-confinement hetero-structure-multiquantum-well (SCH-MQW) laser diodes have been fabricated by molecular-beam epitaxy (MBE), and room-temperature pulsed operation at 1.57 ?m has been achieved. This SCH-MQW laser is composed of InGaAs well layers, InGaAlAs quaternary barrier layers, and InAlAs and InP cladding layers.     

GaInP/AlGaInP double-heterostructure laser grown on a(111)B-oriented GaAs substrate by metalorganic chemical vapourdeposition

Room temperature continuous-wave operation of a Ga_0.5In _0.5P/(Al_0.5Ga_0.5)_0.5In _0.5P double-heterostructure laser grown on a (111)B-oriented GaAs substrate by metalorganic chemical vapour deposition was obtained for the first time. The threshold current was 99 mA. The emission wavelength was around 650 nm, which was about 30 nm shorter than that of a similar laser grown on a (100)-oriented GaAs substrate     

Interfaces of InAsP/InP multiple quantum wells grown by metalorganic vapor phase epitaxy

We present results of the growth of InAs_xP_1−x/InP strained heterostructures by low pressure metalorganic vapor phase epitaxy. A large incorporation of arsenic into the InAsP ternary was observed using tertiarylbutylarsine as precursor. High resolution x-ray diffraction, photoluminescence, and optical absorption measurements for InAsP/InP strained multiple quantum wells reveal that the InAsP/InP interface is very sensitive to growth interruption. A systematic study of a growth in terruption sequence designed to improve the InAs/InP interface was carried out. For nonoptimal growth interruption procedures a large density of interface states is created, probably as a consequence of compositional modifications within the interface region. We find that the absorption spectrum may reveal a significant density of interface states. Thus, photoluminescence on its own is insufficient to characterize the interface roughness even for structures showing narrow low-temperature photoluminescence peaks. We also observe an enhancement of the As content for structures grown on InP (001) relative to those simultaneously grown on InP(001) two degrees off toward [100], which suggests that the composition of As in the ternary is limited by its surface diffusion.     

High-current-gain InGaAs/InP double-heterojunction bipolartransistors grown by metal organic vapor phase epitaxy

By inserting a thin n-InP layer between the p⁺-InGaAs base and the n-InP collector excellent transistor characteristics were obtained. The DE and small-signal current gains were 7000 and 11000, respectively, which are the highest values reported for transistors of this type. The transistors were also operated in a collector-up configuration with DE gains as large as 2500     

Effects of rapid thermal annealing on nitrided gate oxide grown on 4H-SiC

The electrical characteristics of thermally nitrided gate oxides on n-type 4H-SiC, with and without rapid thermal annealing processes, have been investigated and compared in this paper. The effects of annealing time (isothermal annealing) and annealing temperature (isochronal annealing) on the gate oxide quality have also been systematically investigated. After rapid isothermal and isochronal annealings, there has been a significant increase in positive oxide-charge density and in oxide-breakdown time. A correlation between the density of the positive oxide charge and the oxide breakdown reliability has been established. We proposed that the improvement in the oxide-breakdown reliability, tested at electric field of 11 MV/cm, is attributed to trapping of injected electron by the positive oxide charge and not solely due to reduction of SiC-SiO₂ interface-trap density.     

InGaN multiple quantum well laser diodes grown by molecular beam epitaxy

The first InGaN multiple quantum well laser diodes produced by molecular beam epitaxy are reported. Ridge waveguide lasers have been demonstrated at room temperature under pulsed current injection conditions. The lasers emit at a wavelength of approximately 400 nm with a spectral line-width of less than 0.2 nm, and a threshold current density of /spl sim/30 kA cm/sup -2/.     

GaInAs metal/semiconductor/metal photodetectors with Fe:InP barrier layers grown by chemical beam epitaxy

A GaInAs metal/semiconductor/metal (MSM) photodetector with a dark current less than 1 mu A is described. An Fe-doped InP layer was introduced between the metal and the GaInAs absorbing layer to improve the Schottky barrier height. A breakdown voltage of 30 V was achieved. A DC quantum efficiency of 64% and an impulse response, 1/e fall time of 190 ps were measured for a 20 mu m*100 mu m device. The layer structure is very attractive for integration with high-performance GaInAs/InP FETs.<>     

Improving the performance of organic light-emitting diodes containing BCP/LiF/Al by thermal annealing

In this paper, we examined the effect of post-packaging annealing on the performance of organic light-emitting diodes containing tris-(8-hydroxyquinoline) aluminum (Alq,) or 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) in direct contact with a LiF-Al bilayer cathode. The detailed electroluminescent (EL) characteristics were compared before and after annealing at 70 /spl deg/C for 5 hrs. It was found that better luminous efficiency as well as greater power efficiency could be achieved for devices with BCP/LiF/Al structure. However, other devices consisting of Alq/sub 3//LiF/Al were less affected. It is believed that the thermal treatment helps to enhance the electron injection for the former, and less helpful for the latter.     

Patterning by rapid thermal annealing of GaAs layers grown on diluted nitride QWs

The structural characterization of hole patterns on GaAs cap layers grown on GaInNAs quantum wells (QWs) created by rapid thermal annealing is shown in this work. The effect of annealing temperature on the hole size, as well as the impact of the ion density present during the growth of the QW on the formation of this hole pattern, is presented. Structural (atomic force, scanning electron and transmission electron microscopy) and optical characterization (cathodoluminescence) of the samples is presented. The structure of the planes forming the walls and base of these holes is proposed.     

Initial stages of InP/GaP (100) and (111)A,B grown by metal organic chemical vapor deposition

The initial stages of the three-dimensional metal organic vapor phase epitaxy growth of InP/GaP (100) and (111)_A,B were studied by atomic force microscopy (AFM) and Rutherford back scattering (RBS). We have shown that the heteroepitaxial growth takes place under Stranski–Krastanov mode (layer by layer and dislocation free island growth). By combining RBS and AFM results, we show that the wetting layer is about 0.51 and 0.4 nm for (100) and (111)_A,B orientated substrates, respectively. The critical thickness is found to depend on the substrate orientation. However, we show by the AFM technique that the shape, the height and the size of uncapped InP/GaP self-organized nanostructures depend on the amount of InP deposited and on the substrate orientation. In particular, the structure grown on (111)_A,B substrate presents higher islands than the structure grown on (100). Therefore, the formation of nanostructures on substrates different from (100) is an interesting possibility to be investigated.     

SiC/Si heterojunction diodes fabricated by self-selective and byblanket rapid thermal chemical vapor deposition

SiC/Si heterojunction diodes have been fabricated by two different rapid thermal chemical vapor deposition (RTCVD) processes: a localized self-selective growth and blanket growth. The self-selective growth of crystalline cubic (β) SiC was obtained by propane carbonization of the Si substrate in regions unprotected by an SiO₂ layer, producing planar diodes. Mesa diodes were fabricated using the blanket growth of polycrystalline β-SiC produced by the decomposition of methylsilane (CH₃SiH₃). The SiC/Si heterojunction diodes show good rectifying properties for both device structures. Reverse breakdown voltage of 50 V was obtained with the self-selective SiC/Si diode. The mesa diodes exhibited even higher breakdown voltages (V_br) of 150 V and excellent ideality factors of 1.06 at 25°C. The high V_br and good forward rectifying characteristics indicate that the SiC/Si heterojunction diode represents a promising approach for the fabrication of wide-gap emitter SiC/Si heterojunction bipolar transistors     

InP/InGaAsP/InGaAs avalanche photodiodes grown by chemical beam epitaxy

InP/InGaAsP/InGaAs avalanche photodiodes with separate absorption, grading, and multiplication regions (SAGM-APD's) have been fabricated from wafers grown by chemical beam epitaxy (CBE). These APD's exhibit low dark current (<25 nA at 90 percent of breakdown), low capacitance (≈0.2 pF), and good responsivity (0.75 A/ W at 1.3 µm). The pulse response, which is relatively independent of avalanche gain, is characterized by rise and fall times of approximately 1.4 ns.     

GaInAsP/InP surface emitting lasers grown by chemical beam epitaxy

A GaInAsP/InP surface emitting laser has been demonstrated grown by chemical beam epitaxy (CBE) for the first time. The device has a 30 mu m round-low mesa with a 1.0 mu m active layer. The threshold current as low as 2.7 mA (455 A/cm/sup 2/) was obtained under 77 K CW operation (=1.43 mu m). This is the lowest value of long wavelength SE lasers ever reported. These results show the possibility of realising high performance SE lasers grown by CBE.<>