The mode competition,instability, and second harmonic generation in dual-frequency InGaAs/GaAs/InGaP lasers

InGaAs/GaAs/InGaP-based heterolasers with asymmetrically grown quantum wells of two types are developed. For the first time, dual-wavelength operation and second-harmonic generation are realized in these lasers over a wide range of injection currents: from 0.2 A in CW mode up to 10 A in injection with 200-ns-long pulses. Previously unknown special features of such a generation are experimentally revealed and interpreted in terms of the competition and coexistence of various short-and long-wavelength modes, including the “whispering-gallery” modes.     

MOCVD-grown broad area InGaAs/GaAs/InGaP laser diodes

A MOCVD technology for growth of InGaAs/GaAs/InGaP laser heterostructures on a modified Epiquip VP-50-RP installation was developed. Mesa stripe laser diodes with threshold current density J _th=100–200 A/cm², internal optical loss α_i=1.3–1.7 cm^?1, and internal quantum efficiency η_i=60–70% have been fabricated. A CW output optical power of 5 W has been obtained for a single 100-µm-wide aperture mesa stripe laser diode emitting at 1.03 µm. It is shown that use of AlGaAs waveguide layers, which increase the conduction band barrier offset, lowers the temperature sensitivity of laser heterostructures within the temperature range 10–80°C.     

Method for narrowing the directional pattern of an InGaAs/GaAs/AlGaAs multiwell heterolaser

A semiconductor laser with a new waveguide is developed. It allows significant narrowing of the directional pattern (to 4° in the plane perpendicular to the p–n junction). In the used waveguide, the minimum excess of the effective refractive index n_eff of the excitation mode over the substrate refractive index n_s (n_eff–n_s ? 1) is provided by selecting the thickness of Al_0.3Ga_0.7As confinement layers, which significantly increases the waveguide mode size and leads to directional-pattern narrowing.     

Performance dependence of InGaP/InGaAs/GaAs pHEMTs on gatemetallization

The performance of InGaP-based pHEMTs as a function of gate metallization is examined for Mo/Au, Ti/Au, and Pt/Au gates. DC and microwave performance of pHEMT's with 0.7-μm gate lengths is evaluated. Transconductance, threshold voltage, f_t, and f_max are found to depend strongly on gate metallization. High-speed performance is achieved, with f_t of 41.3 GHz and f _max of 101 GHz using Mo/Au gates. The difference in performance between devices with different gate metallizations is postulated to be due to a combination of the difference in Schottky barrier heights and different gate-to-channel spacings due to penetration of the gate metal into the InGaP barrier layer     

Gate length scaling in high performance InGaP/InGaAs/GaAs pHEMTs

The performance of InGaP-based pHEMTs as a function of gate length has been examined experimentally. The direct-current and microwave performance of pHEMTs with gate lengths ranging from 1.0-0.2 μm has been evaluated. Extrinsic transconductances from 341 mS/mm for 1.0 μm gate lengths to 456 mS/mm for 0.5 μm gate lengths were obtained. High-speed device operation has been verified, with f_t of 93 GHz and f_max of 130 GHz for 0.2 μm gate lengths. The dependence of DC and small-signal device parameters on gate length has been examined, and scaling effects in InGaP-based pHEMT's are examined and compared to those for AlGaAs/InGaAs/GaAs pHEMTs. High-field transport in InGaP/InGaAs heterostructures is found to be similar to that of AlGaAs/InGaAs heterostructures. The lower ϵ_r of InGaP relative to AlGaAs is shown to be responsible for the early onset of short-channel effects in InGaP-based devices     

Simulated analysis for InGaP/GaAs heterostructure-emitter bipolar transistor with InGaAs/GaAs superlattice-base structure

A novel InGaP/GaAs heterostructure-emitter bipolar transistor (HEBT) with InGaAs/GaAs superlattice-base structure is proposed and demonstrated by two-dimensional analysis. As compared with the traditional HEBT, the studied superlattice-base device exhibits a higher collector current, a higher current gain of 246, and a lower base–emitter (B–E) turn-on voltage of 0.966 V at a current level of 1 μA, attributed to the increased charge storage of minority carriers in the InGaAs/GaAs superlattice-base region by tunneling behavior. The low turn-on voltage can reduce the operating voltage and collector–emitter offset voltage for low power consumption in circuit applications.     

Surface passivation of InGaP/InGaAs/GaAs pseudomorphic HEMTs with ultrathin GaS film

We report on the successful surface passivation of wide recess InGaP/InGaAs/GaAs pseudomorphic HEMTs with MBE-grown ultrathin GaS film (2 nm) employing a single precursor, tertiarybutyl-galliumsulfide-cubane ([(t-Bu)GaS]/sub 4/). At the recess length of 1.1 /spl mu/m, a GaS-passivated device with a 0.5-/spl mu/m gate length has the maximum transconductance (g/sub m max/) of 347 mS/mm, which is about 40% higher than that of 240 mS/mm for a device without GaS passivation. We found that one of the causes of an increased g/sub m max/ is the decrease of sheet resistance on the recessed surface because GaS passivation has reduced the depletion layer. Meanwhile, the two-terminal gate-to-drain reverse breakdown voltage (BV/sub gd/) was reduced after GaS passivation. The BV/sub gd/ is independent of the recess length between gate and drain (L/sub gd/) for GaS-passivated devices, unlike that for devices without GaS passivation. According to our calculation of the BV/sub gd/ involving the effects of impact ionization and the interface state, the BV/sub gd/ becomes almost independent of the L/sub gd/, when the interface state density (N/sub int/) is below 1/spl times/10/sup 12/ cm/sup -2/. Then, the calculated surface potential at the recess region is less than 0 eV. This result suggests that GaS passivation can remarkably reduce the N/sub int/ at the recess region.     

Highly doped InGaP/InGaAs/GaAs pseudomorphic HEMT's with 0.35 μmgates

We fabricated 0.35-μm gate-length pseudomorphic HEMT DCFL circuits using a highly doped thin InGaP layer as the electron supply layer. The InGaP/InGaAs/GaAs pseudomorphic HEMT grown by MOVPE is suitable for short gate-length devices with a low supply voltage since it does not show short channel effects even for gate length down to 0.35 μm. We obtained a K value of 555 mS/Vmm and a transconductance g_m of 380 mS/mm for an InGaP layer 18.5 nm thick. Fabricated 51-stage ring oscillators show the basic propagation delay of 11 ps and the power-delay product of 7.3 fJ at supply voltage of V_DD of 1 V, and 13.8 ps and 3.2 fJ at V_DD of 0.6 V for gates 10 μm wide     

High temperature, high power InGaAs/GaAs quantum-well lasers withlattice-matched InGaP cladding layers

The authors report the high-temperature and high-power operation of strained-layer InGaAs/GaAs quantum well lasers with lattice-matched InGaP cladding layers grown by gas-source molecular beam epitaxy. Self-aligned ridge waveguide lasers of 3-μm width were fabricated. These lasers have low threshold currents (7 mA for 250-μm-long cavity and 12 mA for 500-μm-long cavity), high external quantum efficiencies (0.9 mW/mA), and high peak powers (160 mW for 3-μm-wide lasers and 285 mW for 5-μm-wide laser) at room temperature under continuous wave (CW) conditions. The CW operating temperature of 185°C is the highest ever reported for InGaAs/GaAs/InGaP quantum well lasers, and is comparable to the best result (200°C) reported for InGaAs/GaAs/AlGaAs lasers     

TE-to-TM mode conversion in GaAs/AlGaAs superlattice waveguide

Intrinsic phase matching between a TE and a TM mode is obtained in a GaAs/AlGaAs superlattice waveguide, fabricated by Zn diffusion induced disordering, as a result of the birefringent waveguiding properties of the superlattice in combination with a proper choice of the waveguide geometry. As a consequence, up to 90% polarisation conversion is demonstrated without the application of phase matching techniques.<>     

On the InGaP/GaAs/InGaAs camel-like FET for high-breakdown,low-leakage, and high-temperature operations

A new field-effect transistor using a high-barrier n⁺ -GaAs/p⁺-InGaP/n-GaAs camel-like gate and GaAs/InGaAs heterostructure-channel has been fabricated successfully and demonstrated. Experimentally, an ultra high gate-drain breakdown voltage of 52 V, a high drain-source operation voltage over 20 V with low leakage currents, and a high drain-source off-state breakdown voltage of 39.7 V are obtained for a 1×100 μm² device. The high breakdown behavior is attributed to the use of high barrier camel-like gate and heterostructure channels to reduce the undesired leakage current. Furthermore, the studied device also shows high breakdown behavior in a high temperature environment and good microwave characteristics. Therefore, based on these characteristics, the studied device is suitable for high-breakdown, low-leakage, and high-temperature applications     

基于MBE生长的一种Be掺杂InGaAs基区的新结构InGaP/InGaAs/GaAs DHBT

报道了一种以InGaAs为基区的新结构InGaP/InGaAs/GaAs双异质结晶体管,获得了直流性能良好的器件.其共射直流增益β达到100,残余电压Voffset约为0.4V,膝点电压Vknee约为1V,击穿电压BVceo超过10V,器件的基极和集电极电流理想因子分别为nb=1.16,nc=1.11,可应用于低功耗、高功率领域.     

基于MBE生长的一种Be掺杂InGaAs基区的新结构InGaP/InGaAs/GaAs DHBT

报道了一种以InGaAs为基区的新结构InGaP/InGaAs/GaAs双异质结晶体管,获得了直流性能良好的器件.其共射直流增益β达到100,残余电压Voffset约为0.4V,膝点电压Vknee约为1V,击穿电压BVceo超过10V,器件的基极和集电极电流理想因子分别为nb=1.16,nc=1.11,可应用于低功耗、高功率领域.     

A novel InGaP/InGaAs/GaAs double /spl delta/-doped pHEMT with camel-like gate structure

The author reports a novel InGaP/InGaAs/GaAs double delta-doped pseudomorphic high-electron mobility transistor (pHEMT) with n/sup +/-GaAs/p/sup +/-InGaP/n-InGaP camel-like gate structure grown by MOCVD. Due to the p-n depletion from the p/sup +/-InGaP gate to the channel region and the presence of /spl Delta/Ec at the InGaP/InGaAs heterostructure, the turn-on voltage of gate is larger than 1.7 V. For a 1/spl times/100-/spl mu/m/sup 2/ device, the experimental results show an extrinsic transconductance of 107 mS/mm and a saturation current density of 850 mA/mm. Significantly, an extremely broad gate voltage swing larger than 6 V with above 80% maximum g/sub m/ is obtained. Furthermore, the unit current cut-off frequency f/sub T/ and maximum oscillation frequency are up to 20 and 32 GHz, respectively. The excellent device performance provides a promise for linear and large signal amplifiers and high-frequency circuit applications.     

Metamorphic InAlAs/InGaAs enhancement mode HEMTs on GaAs substrates

In_0.5Al_0.5As/In_0.5Ga_0.5 As HEMTs have been grown metamorphically on GaAs substrates oriented 6° off (100) toward (111)A using a graded InAlAs buffer. The devices are enhancement mode and show good dc and RF performance. The 0.6-μm gate length devices have saturation currents of 262 mA/mm at a gate bias of 0.7 V and a peak transconductance of 647 mS/mm. The 0.6 μm×3 mm devices tested on-wafer have output powers up to 30 mW/mm and 46% power-added-efficiency (PAE) at 1 V drain bias and 850 MHz. When biased and matched for best efficiency performance, this same device has up to 68% PAE at V_d=1 V     

InGaP/InGaAs MOS-PHEMT with a nanoscale liquid phase-oxidized InGaP dielectric

InGaP/InGaAs metal–oxide–semiconductor (MOS) pseudomorphic high-electron-mobility transistor (PHEMT) with a nanoscale liquid phase-oxidized InGaP as the gate dielectric is demonstrated. Not only does the MOS-PHEMT have the advantages of the MOS structure, but it also has high-carrier density and a high-mobility 2DEG channel. Using selective oxidation of InGaP by liquid phase oxidation, the MOS-PHEMT can be fabricated without additional recess processes. The MOS-PHEMT exhibits larger transconductance, lower gate leakage current, higher breakdown voltage, higher cut-off frequency, lower minimum noise figure, and higher power-added efficiency than does its counterpart (reference PHEMT). The interface roughness effect on the DC and RF performance of devices is also discussed.     

The study of δ-doped InGaP/InGaAs/GaAs pseudomorphic high electron mobility transistor

An enhancement-mode pseudomorphic high electron mobility transistor (E-mode pHEMT) with In_0.49Ga_0.51P/In_0.25Ga_0.75As/GaAs structure is studied in this paper. The two-dimensional device simulator, MEDICI, is used to solve the Poisson's equation and the electron/hole current continuity equations. An optimized δ-doped InGaP/InGaAs pHEMT structure is found to be superior to the conventional AlGaAs/InGaAs pHEMT. It reveals that the maximum drain-source current (I_DS) goes up to 1600 mA/mm and transconductance (G_m) is 2120 mS/mm.     

Self-organized nanoscale InP islands in an InGaP/GaAs host and InAs islands in an InGaAs/InP host

Arrays of strained nanoscale InP islands in an In_0.49Ga_0.51P host on a GaAs(100) substrate and InAs islands in a In_0.53Ga_0.47As host on an InP(100) substrate are obtained by metalorganic vapor-phase epitaxy (MOVPE). Their structural and photoluminescence properties are investigated. It is shown that the nanoscale islands that are formed measure 80 nm (InP/InGaP) and 25–60 nm (InAs/InGaAs). The photoluminescence spectra of the nanoscale islands display bands in the wavelength ranges 0.66–0.72 and 1.66–1.91 μm at 77 K with maxima whose position does not vary as the effective thickness of InP and InAs increases. The radiation efficiency of the nanoscale InP islands is two orders of magnitude greater than the luminescence intensity of the InAs islands. Fiz. Tekh. Poluprovodn. 33, 858–862 (July 1999)     

新结构InGaP/GaAs/InGaP DHBT生长及特性研究

设计并生长了一种新的InGaP/GaAs/InGaP DHBT结构材料,采用在基区和集电区之间插入n+-InGaP插入层结构,以解决InGaP/GaAs/InGaP DHBT集电结导带尖峰的电子阻挡效应问题。采用气态源分子束外延(GSMBE)技术,通过优化生长条件,获得了高质量外延材料,成功地生长出带有n+-InGaP插入层结构的GaAs基InGaP/GaAs/InGaP DHBT结构材料。采用常规的湿法腐蚀工艺,研制出发射极面积为100μm×100μm的新型结构InGaP/GaAs/InGaP DHBT器件。直流特性测试的结果表明,所设计的集电结带有n+-InGaP插入层的InGaP/GaAs/InGaP DHBT器件开启电压约为0.15V,反向击穿电压达到16V,与传统的单异质结InGaP/GaAs HBT相比,反向击穿电压提高了一倍,能够满足低损耗、较高功率器件与电路制作的要求。