Characteristics of native-oxide-confined InGaP-(AlxGa1-x)0.5In0.5P quantum-well ridgewaveguide lasers

We report 670-nm native-oxide confined GaInP-(Al_xGa_1-x)_0.5In_0.5P quantum-well ridge waveguide laser diodes. The devices are fabricated from a compressively strained GaInP-(Al_xGa_1-x)_0.5In_0.5P quantum-well separate confinement heterostructure laser structure. Wet chemical etching and wet oxidation process are used to form native oxide confined ridge waveguides. The oxidation process converts the p-Al_0.5In_0.5P cladding layer into AlO_x after ridge etch. Laser diodes of 3.5-μm-wide ridge waveguide operate with threshold currents below 13.5 mA and differential quantum efficiencies over 35%/facet     

Very closely spaced quadspot native-oxide confined 780-nmsemiconductor lasers

We describe the fabrication and characteristics of 7-μm spaced quadspot, independently addressable 785-nm native-oxide confined ridge waveguide laser diodes. The devices are fabricated from an Al_0.1 Ga_0.9As-Al_0.4Ga_0.6As-Al_0.5 In_0.5P quantum-well separate confinement heterostructure laser structure. Wet oxidation of the p-Al_0.5In_0.5P cladding layer is used to form a native oxide for not only ridge waveguide confinement, but also electrical insulation to allow electrical connection to laser stripes. These diodes show excellent performance: uniform threshold currents below 8 mA and differential quantum efficiencies over 35%/facet. The diodes show crosstalk less than 5%     

In0.5(AlxGa1-x)0.5HEMTs for high-efficiency low-voltage power amplifiers: design,fabrication, and device results

In_0.5(Al_xGa_1-x)_0.5 high electron-mobility transistors (HEMTs) are expected to have higher two-dimensional electron gas density and larger current drive capability than both Al_0.23Ga_0.77As and In_0.5Ga _0.5P HEMTs due to the improved conduction-band offsets. In this paper, we performed a systematic investigation of the electrical properties of In_0.5(Al_xGa_1-x)_0.5 P (0⩽x⩽1) material system lattice matched to GaAs. By considering the conduction-band offset, direct-to-indirect-band electron transfer, donor-related deep levels, and Schottky barrier height, a relatively narrow range of the Al content 0.2⩽x⩽0.3 was found to be the optimum for the design of In_0.5(Al_xGa_1-x)_0.5 HEMTs. Under 1.2-V operation, power transistors with the optimum aluminum composition show high drain current density, high transconductance, and excellent power-added efficiency (65.2% at 850 MHz). These results demonstrate that InAlGaP HEMTs are promising candidates for high-efficiency low-voltage power applications     

Organometallic vapor phase epitaxial growth of (AlxGa1-x)0.5In0.5P and its heterostructures

Low pressure organometallic vapor-phase epitaxial growth of Ga_0.5In_0.5P and (Al_xGa_1-x) _0.5In_0.5P is examined. Epitaxial layers of bulk materials are characterized using photoluminescence, electroreflectance, Raman scattering spectroscopy, and surface morphology studies to determine lattice match and optimum growth conditions. Lattice matching at the growth temperature produces featureless growth surfaces, while lattice matching at room temperatures results in minimum photoluminescence linewidth but cracked surfaces due to tensile strain during growth. Raman scattering spectra of the quaternary reveal a three mode structure, with spectral peaks due to GaP-like, InP-like, and AIP-like LO phonons. Heterostructures are investigated including quantum shifts from a series of superlattices. These materials are incorporated in double-heterostructure lasers and single-quantum-well laser with graded-index separate confinement heterostructure     

RIE gate-recessed(Al0.3Ga0.7)0.5In0.5P/InGaAsdouble doped-channel FETs using CHF3+BCl3 mixingplasma

BCl₃+CHF₃ gas mixtures for the reactive ion etching process were applied to the gate-recess for fabricating (Al_0.3Ga_0.7)_0.5In_0.5P quaternary heterostructure double doped-channel FET's (D-DCFET), where a high uniformity of Vth was achieved. With the merits of this wide bandgap (Al_0.3Ga_0.7)_0.5In_0.5P layer, microwave power performance of this heterostructure D-DCFET demonstrates a compatible performance for devices fabricated on AlGaAs/InGaAs heterostructures     

Tensile-strained AlGaAsP and InGaAsP-(AlGa)0.5In0.5P quantum well laser diodes for TM-mode emission in the wavelengthrange 650 <λ<850 nm

TM-polarized laser emission is demonstrated at wavelengths longer than 650 nm, for (AlGa)_0.5In_0.5P-based laser diodes. These structures contain tensile-strained AlGaAsP or InGaAsP quantum well active regions, which are capable of spanning a wavelength range of roughly 650-850 nm, for TM-mode lasers on GaAs substrates. This represents an extension of the wavelength range available from typical GaInP-(AlGa)_0.5In_0.5P lasers, where the requirement for biaxial tension limits the TM-mode wavelengths to less than 650 nm. In addition, compared to AlGaAs confining structures, the high-bandgap (AlGa)_0.5In_0.5P confinement structure used here makes AlGaAs(P) active regions feasible at shorter wavelengths, with good performance maintained for 670<λ<700 mn. Likewise, the wavelength range 700<λ<750 nm, where AlGaAs laser characteristics are diminished, becomes accessible using these materials     

Avalanche breakdown in (AlxGa1x)0.52In0.48P pin junctions

The avalanche breakdown behaviour of (Al_xGa_1-x )_0.52In_0.48P has been investigated by growing a series of pin diode structures and by measuring the reverse leakage currents until the onset of avalanche breakdown. Comparing the breakdown voltage (V_bd) with that of GaAs, significant increases are obtained, with AlInP having in excess of twice the V_bd of GaAs     

Electron transport across bulk(AlxGa1-x)0.5In0.5P barriersdetermined from the I-V characteristics of n-i-n diodes measured between60 and 310 K

The electron transport characteristics of five n-i-n diodes with (Al_xGa_1-x)_0.5In_0.5P intrinsic barrier regions of various aluminum composition x were determined from the measured I-V characteristics between 60 and 310 K. From these measurements, three different transport regimes were identified. Fowler-Nordheim tunneling was observed at temperatures below 215, 260, 110, 150, and 120 K for aluminum compositions of x=0.4, 0.5, 0.6, 0.7, and 1.0, respectively, with applied electric fields in excess of 5 MV/m. The temperature dependence of the Fowler-Nordheim tunneling currents is shown in AlGaInP for the first time with direct bandgap AlGaInP exhibiting a strong linear decrease in apparent barrier height with increasing temperature. The measured barrier height using the thermionic emission model yields values close to the expected conduction band offset between the GaInP spacer layers and the AlGaInP intrinsic barriers, as measured using high-pressure photoluminescence, and provides a novel technique for measuring the direct-indirect crossover composition in AlGaInP. It is shown that the lowest lying conduction band in AlGaInP is the dominant barrier to electron transport. This has important implications for the design of AlGaInP laser diodes     

Characteristics of short-wavelength (617<λ<640 nm) Ga0.4In0.6P/(AlxGa1-x)0.5In0.5P strained, thin multiple-quantum-well lasers

The authors examine the operating characteristics of short wavelength (617<λ<640 nm) AlGaInP lasers containing three thin (~20 Å) compressively strained Ga_0.4In_0.6 P/(Al_0.6Ga_0.4)_0.5In_0.5 P quantum wells and Al_0.5In_0.5P cladding layers, grown by low pressure organometallic vapor phase epitaxy. At room temperature, wavelengths as short as 617 nm have been achieved, with pulsed threshold current density of 2.5 kA/cm². As a result of greater electron confinement at longer wavelengths, the threshold, and its temperature sensitivity, are improved     

Single- and double-heterojunction pseudomorphic In0.5(Al0.3Ga0.7)0.5P/In0.2Ga0.8As high electron mobility transistors grown by gas sourcemolecular beam epitaxy

In_0.5(Al_0.3Ga_0.7)_0.5 P/In_0.2Ga_0.8As single- and double-heterojunction pseudomorphic high electron mobility transistors (SH-PHEMTs and DH-PHEMTs) on GaAs grown by gas-source molecular beam epitaxy (GSMBE) were demonstrated for the first time. SH-PHEMTs with a 1-μm gate-length showed a peak extrinsic transconductance g_m of 293 mS/mm and a full channel current density I_max of 350 mA/mm. The corresponding values of g_m and I_max were 320 mS/mm and 550 mA/mm, respectively, for the DH-PHEMTs. A short-circuit current gain (H₂₁) cutoff frequency f_T of 21 GHz and a maximum oscillation frequency f_max of 64 GHz were obtained from a 1 μm DH device. The improved device performance is attributed to the large ΔE_c provided by the In_0.5(Al_0.3Ga_0.7)_0.5P/In _0.2Ga_0.8As heterojunctions. These results demonstrated that In_0.5(Al_0.3Ga_0.7)_0.5P/In _0.2Ga_0.8As PHEMT's are promising candidates for microwave power applications     

Characteristics of a In0.52(AlxGa1-x)0.48As/In0.53Ga0.47As(0⩽x⩽1) heterojunction and its application onHEMT's

The quaternary In_0.52(Al_xGa_1-x) _0.48As compound on InP substrates is an important material for use in optoelectronic and microwave devices. We systematically investigated the electrical properties of quaternary In_0.52(Al_xGa_1-x)_0.48As layers, and found a 10% addition of Ga atoms into the InAlAs layer improves the Schottky diode performance. The energy bandgap (E_g ) for the In_0.52(Al_xGa_1-x)_0.48As layer was (0.806+0.711x) eV, and the associated conduction-band discontinuity (ΔE_c), in the InAlGaAs/In_0.53Ga_0.47 As heterojunction, was around (0.68±0.01)ΔE_g . Using this high quality In_0.52(Al_0.9Ga_0.1)_0.48As layer in the Schottky and buffer layers, we obtained quaternary In_0.52(Al_0.9Ga_0.1)_0.48As/In _0.53Ga_0.47As HEMTs. This quaternary HEMT revealed excellent dc and microwave characteristics. In comparison with the conventional InAlAs/InGaAs HEMT's, quaternary HEMT's demonstrated improved sidegating and device reliability     

Ga0.51In0.49P/In0.15Ga0.85As/GaAs pseudomorphic doped-channel FET with high-current densityand high-breakdown voltage

Ga_0.51In_0.49P/In_0.15Ga_0.85 As/GaAs pseudomorphic doped-channel FETs exhibiting excellent DC and microwave characteristics were successfully fabricated. A high peak transconductance of 350 mS/mm, a high gate-drain breakdown voltage of 31 V and a high maximum current density (575 mA/mm) were achieved. These results demonstrate that high transconductance and high breakdown voltage could be attained by using In_0.15Ga_0.85As and Ga_0.51In_0.49P as the channel and insulator materials, respectively. We also measured a high-current gain cut-off frequency f_t of 23.3 GHz and a high maximum oscillation frequency f_max of 50.8 GHz for a 1-μm gate length device at 300 K. RF values where higher than those of other works of InGaAs channel pseudomorphic doped-channel FETs (DCFETs), high electron mobility transistors (HEMTs), and heterostructure FETs (HFETs) with the same gate length and were mainly attributed to higher transconductance due to higher mobility, while the DC values were comparable with the other works. The above results suggested that Ga_0.51In_0.49P/In_0.15Ga_0.85 As/GaAs doped channel FET's were were very suitable for microwave high power device application     

Low-loss Bragg-reflector lateral-transverse-mode confinement inAlGaInP red laser

A low-loss Bragg-reflector-waveguide (BRW) structure is proposed for AlGaInP red lasers. This BRW laser uses (AlGaInP/GaAs)_n Bragg-reflector (BR) block layers in place of conventional GaAs block layers. Propagating-mode calculations reveal that an aluminum content (x) lower than 0.2 for (Al_xGa_1-x)_0.5In _0.5P in the BR block layers is sufficient for reducing mode loss together with confining the lateral transverse mode. Mode loss in the (AlGaInP/GaAs)_n BR region is reduced resonantly to one-third that of a conventional GaAs block region. This reduction originates from a combination of Bragg reflection and the low absorption loss in the AlGaInP crystal. The refractive-index step, formed at the edge of a ridge stripe by the BR block layers, is around 1×10^-2     

Al0.25In0.75P/Al0.48In0.52As/Ga0.35In 0.65As graded channelpseudomorphic HEMT's with high channel-breakdown voltage

A new Al_0.25In_0.75P/Al_0.48In_0.52 As/Ga_0.35In 0_.65As pseudomorphic HEMT where the InAs mole fraction of the Ga_1-xIn_xAs channel was graded (x=0.53→0.65→0.53) is described. The modification of the quantum well channel significantly improved breakdown characteristics. In addition, use of an Al_0.25In_0.75P Schottky layer increased the Schottky barrier height. Devices having 0.5 μm gate-length showed g_m of 520 mS/mm and I_max of 700 mA/mm. The gate-drain (BV_g-d) and source-drain (BV_d-s ) breakdown voltages were as high as -14 and 13 V, respectively. An f_T of 70 GHz and f_max of 90 GHz were obtained     

Superposed multiquantum barriers for InGaAlP heterojunctions

In a visible-light laser using In_0.5(Ga_1-xAl _x)_0.5P (0⩽x⩽1), the conduction-band discontinuity at the interface between the active layer and clad layer is not large enough to strongly suppress carriers overflowing into the clad layer, unlike in the GaAlAs system. A multiquantum barrier (MQB) is used to overcome this problem, and the electron-reflecting powers are calculated to determine the characteristics of this suppression. Electron-reflecting powers are calculated for a high-power, high-temperature laser with an In_0.5 Ga_0.5P active layer, an In_0.5Ga_0.15 clad layer, and a set of superposed MQBs, and for a short-wavelength (λ:586-nm) laser composed of an In_0.5Ga_0.33Al_0.17P active layer, an In _0.5Ga_0.15Al_0.35P clad layer, and a set of superposed MQBs     

The effect of high compressive strain on the operation of AlGaInPquantum-well lasers

In this paper we describe the properties of Ga_xIn_1-xP-(Al_yGa_1-y) _0.52In_0.48P strained quantum-well (QW) lasers at compressive strains of greater than 1%. Structures containing single 100-Å Ga_xIn_1-xP QW's of different compositions have been grown by low-pressure metal organic chemical vapor deposition (MOCVD) with the intention of studying the physical mechanisms which inhibit the operation of strained lasers at high values of compressive strain. In these lasers, we observe a monotonic increase in threshold current with increasing strain between 1% and 1.7%. We show that the increase in threshold current can be attributed to increased optical losses and we measure an increase in the optical mode loss from 10 to 45 cm^-1 with increasing strain. Using transmission electron microscopy (TEM), we are able to link the increased optical losses at high strain with a strain-induced growth nonuniformity in the active region of the device similar to the Stranski-Krastanov growth mode, which results in the formation of islands in the active region on a 100-nm-length scale     

Strain-induced modifications of the band structure ofInxGa1-xP-In0.5Al0.5Pmultiple quantum wells

The effect of strain on the band structure of In_xGa_1-xP-In_0.5Al_0.5P multiple quantum wells (MQW's) has been investigated from high-pressure and low-temperature photoluminescence measurements. The biaxial strain in the wells was varied between +0.6% compressive to -0.85% tensile strain by changing the well composition x from 0.57 to 0.37. Strain increases the valence band offsets in either tensile or compressively strained structures. Whereas relatively insensitive to tensile strain, the valence band offsets showed a strong dependence on the magnitude of the compressive strain. Good agreement is found between the measured valence band offsets and those predicted by the model solid theory, except for the largest compressively strained MQW's, for which the model calculations underestimate the measured valence band offset. Strain and the associated variations in composition also modified the separation among the well states associated with Γ_1c, L_1c , and X_1c. From these results, the bandgaps of each conduction band extrema were calculated in In_xGa_1-xP for 0.37相似文献   

610-nm band AlGaInP single quantum well laser diode

The short-wavelength limits of AlGaInP visible laser diodes with Al_0.5In_0.5P cladding layers, and Ga_xIn _1-xP single quantum well (QW) active regions are investigated. Good performance is maintained throughout the 620 nm band, but the characteristics rapidly degrade in the 610 nm band. Biaxial-compression and -tension were compared, with the case of tension yielding slightly better performance. Using a 25 Å Ga_0.45 In_0.55P QW, a wavelength of 614 nm was obtained, while a 50 Å Ga_0.6In_0.4P QW emitted at 620 nm with a threshold current density of 0.8 kA/cm². These results with thin single QWs indicate the effectiveness of using an Al_0.5In_0.5P cladding layer to reduce electron leakage     

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     

The effect of gate recess profile on device performance ofGa0.51In0.49P/In0.2Ga0.8Asdoped-channel FET's

The effect of gate recess profile on device performance of Ga_0.51In_0.49P/In_0.2Ga_0.8As doped-channel FETs was studied. In the experiment, Ga_0.51In _0.49P/In_0.2Ga_0.8As doped-channel FETs (DCFET's) using triple-recessed gate structure were compared with devices using single-recessed and double-recessed gate structures. It is found that triple-recessed gate approach provides higher breakdown voltage (35 V) than single-recessed (16 V) and double-recessed gate (28 V) approaches. This is attributed to the larger aspect ratio in the triple-recessed gate structure. A unified method to calculate the breakdown voltages of MESFETs, HEMTs and DCFETs (or MISFETs) of any given arbitrary recessed gate profile was proposed and used to explain the experimental results