DC and microwave characteristics of an In0.53Ga0.47As/In0.52Al0.48As modulation-doped quasi-MISFET

The DC and microwave performance of a modulation-doped InGaAs/InAlAs quasi-MISFET structure, grown by molecular beam epitaxy, is reported. Improved performance is obtained with the incorporation of Ti in the source-drain metallisation with which contact resistances as low as 0.1 ?mm are measured. An extrinsic transconductance of 310mS/mm and a best value of fT=32 GHz in a 1.0 ?-gate device are measured at 300 K.     

Persistent photoconductivity and electron mobility in In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As/InP quantum-well structures

The influence of the width of the quantum well L and doping on the band structure, scattering, and electron mobility in nanoheterostructures with an isomorphic In_0.52Al_0.48As/In_0.53Ga_0.47As/In_0.52Al_0.48As quantum well grown on an InP substrate are investigated. The quantum and transport mobilities of electrons in the dimensionally quantized subbands are determined using Shubnikov-de Haas effect measurements. These mobilities are also calculated for the case of ionized-impurity scattering taking into account intersub-band electron transitions. It is shown that ionized-impurity scattering is the dominant mechanism of electron scattering. At temperatures T < 170 K, persistent photoconductivity is observed, which is explained by the spatial separation of photoexcited charge carriers.     

Long-wavelength In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As large-area avalanche photodiodes and arrays

Large-area (500-/spl mu/m diameter) mesa-structure In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiodes (APDs) are reported. The dark current density was /spl sim/2.5/spl times/10/sup -2/ nA//spl mu/m/sup 2/ at 90% of breakdown; low surface leakage current density (/spl sim/4.2 pA//spl mu/m) was achieved with wet chemical etching and SiO/sub 2/ passivation. An 18 /spl times/ 18 APD array with uniform distributions of breakdown voltage, dark current, and multiplication gain has also been demonstrated. The APDs in the array achieved 3-dB bandwidth of /spl sim/8 GHz at low gain and a gain-bandwidth product of /spl sim/120 GHz.     

Direct optical injection locking of monolithically integrated In/sub 0.53/Ga/sub 0.47/As/In/sub 0.52/Al/sub 0.48/As MODFET oscillators

The authors have fabricated monolithically integrated In/sub 0.53/Ga/sub 0.47/As/In/sub 0.52/Al/sub 0.48/As 0.25 mu m gate modulation-doped field effect transistor (MODFET) oscillators. The results of direct optical subharmonic injection locking of these oscillator circuits at 10.159 and 19.033 GHz are presented.<>     

Fabrication and characterization of 100-nm In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As double-gate HEMTs with two separate gate controls

In this letter, we demonstrate successful operation of 100-nm T-gates double-gate high electron mobility transistors with two separate gate controls (V/sub g1s/ /spl ne/ V/sub g2s/). These devices are fabricated by means of adhesive bonding technique using enzocyclocbutene polymer. The additional gate enables the variation of the threshold voltage V/sub th/ in a wide range from -0.68 to -0.12V while keeping high cutoff frequency f/sub t/ of about 170 GHz and high maximum oscillation frequency f/sub max/ of about 200 GHz. These devices are considered as being very effective for millimeter-wave mixing applications and are promising devices for the fabrication of velocity modulation transistor (VMT) (Sakaki et al., 1982).     

Geiger mode operation of an In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode

Low-temperature photon counting with gated mode quenching is demonstrated with separate absorption, charge, and multiplication avalanche photodiodes that have an In/sub 0.52/Al/sub 0.48/As multiplication layer. A minimum of ten dark counts per second and single-photon detection efficiency of 16% were achieved at 130 K.     

High-performance Al/sub 0.48/In/sub 0.52/As/Ga/sub 0.47/In/sub 0.53/As MSM-HEMT receiver OEIC grown by MOCVD on patterned InP substrates

Reports the first demonstration of a new long-wavelength receiver OEIC comprising an AlInAs/GaInAs MSM detector and an AlInAs/GaInAs HEMT preamplifier. The layer structure was grown by LP-MOCVD on patterned InP substrates, which allowed independent optimisation of the MSM detector and HEMT preamplifier. The MSM detector showed the lowest leakage current yet reported and the HEMT exhibited a transconductance of 260 mS/mm. An excellent receiver response to 1.7 Gbit/s NRZ signals has been obtained.<>     

The microwave power performance comparisons of Al/sub x/Ga/sub 1-x/As/In/sub 0.15/Ga/sub 0.85/As (x=0.3, 0.5, 0.7, 1.0) doped-channel HFETs

The properties of doped-channel field-effect transistors (DCFET) have been thoroughly investigated on Al/sub x/Ga/sub 1-x/As/InGaAs (x= 0.3, 0.5, 0.7, 1) heterostructures with various Al mole fractions. In this study, we observed that by introducing a 200-/spl Aring/-thick Al/sub 0.5/Ga/sub 0.5/As (x=0.5) Schottky layer can enhance the device power performance, as compared with the conventional x=0.3 AlGaAs composition system. However, a degradation of the device power performance was observed for further increasing the Al mole fractions owing to their high sheet resistance and surface states. Therefore, Al/sub 0.5/Ga/sub 0.5/As Schottky layer design provides a good opportunity to develop a high power device for power amplifier applications.     

Pseudomorphic In/sub 0.52/Al/sub 0.48/As/In/sub 0.7/Ga/sub 0.3/As HEMTs with an ultrahigh f/sub T/ of 562 GHz

We fabricated decananometer-gate pseudomorphic In/sub 0.52/Al/sub 0.48/As/In/sub 0.7/Ga/sub 0.3/As high-electron mobility transistors (HEMTs) with a very short gate-channel distance. We obtained a cutoff frequency f/sub T/ of 562 GHz for a 25-nm-gate HEMT. This f/sub T/ is the highest value ever reported for any transistor. The ultrahigh f/sub T/ of our HEMT can be explained by an enhanced electron velocity under the gate, which was a result of reducing the gate-channel distance.     

Avalanche noise characteristics of single Al/sub x/Ga/sub 1-x/As(0.3

Groves  C. Chia  C.K. Tozer  R.C. David  J.P.R. Rees  G.J. 《Quantum Electronics, IEEE Journal of》2005,41(1):70-75

Sheet electron concentration at the heterointerface in Al0.48In0.52As/Ga0.47In0.53As modulation-doped structures

Sheet electron concentration at the heterointerface in Al0.48In0.52As/Ga0.47In0.53As modulation-doped structures has been calculated as a function of the spacer layer thickness, the doping concentration in Al0.48In0.52As and the lattice temperature. The calculated results were compared with those for Al0.3Ga0.7As/GaAs structures and also with the experimental data. It is shown that, compared with AlGaAs/GaAs about 1.5 times higher sheet electron concentration can be obtained in AlInAs/GaInAs at the same doping level, which is in good agreement with the experimental results.     

Simulation of quantum transport in monolithic ICs based on In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As RTDs and HEMTs with a quantum hydrodynamic transport model

A new quantum hydrodynamic transport model based on a quantum fluid model is used for numerical calculations of different quantum sized devices. The simulation of monolithic integrated circuits of resonant tunneling structures and high electron mobility transistors (HEMT) based on In/sub 053/Ga/sub 0.47/As-In/sub 052/Al/sub 0.48/As-InP is demonstrated. With the new model, it is possible to describe quantum mechanical transport phenomena like resonant tunneling of carriers through potential barriers and particle accumulation in quantum wells. Different structure variations, especially the resonant tunneling diode area and the gate width of the HEMT structure, show variable modulations in the output characteristics of the monolithic integrated device.     

A 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode array

We report a 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode (APD) array. The mean breakdown voltage of the APD was 57.9 V and the standard deviation was less than 0.1 V. The mean dark current was /spl sim/2 and /spl sim/300 nA, and the standard deviation was /spl sim/0.19 and /spl sim/60 nA at unity gain (V/sub bias/ = 13.5 V) and at 90% of the breakdown voltage, respectively. External quantum efficiency was above 40% in the wavelength range from 1.0 to 1.6 /spl mu/m. It was /spl sim/57% and /spl sim/45% at 1.3 and 1.55 /spl mu/m, respectively. A bandwidth of 13 GHz was achieved at low gain.     

Thermal stability of Al0.48In0.52As/Ga0.47In0.53As/InP heterostructure and its improvement by phosphidization

A drastic decrease in the sheet carrier concentration of modulation-doped Al_0.48In_0.52As/Ga_0.47In_0.53As/InP heterostructures has been observed after O₂ plasma treatment followed by thermal treatment up to 350°C. The decrease in sheet carrier concentration, which is speculated to be caused by both plasma damage and impurities penetrating from the surface of the epilayer, can be suppressed substantially by using PH₃ plasma treatment prior to the O₂ plasma and thermal treatments.     

Optical tuning of monolithic In/sub 0.53/Ga/sub 0.47/As/In/sub 0.52/Al/sub 0.48/As/InP modulation-doped field-effect transistor oscillators at X and R band

The authors have experimentally studied the optical control and optical tuning characteristics of monolithically integrated In/sub 0.53/Ga/sub 0.47/As/In/sub 0.52/Al/sub 0.48/As modulation-doped field-effect transistor (MODFET) oscillators operating in the X and R bands. For a 20 mu W intrinsic photoexcitation on the device, the maximum frequency shift for the X- and R-band oscillators was 8.7 and 11.7 MHz, respectively.<>     

Room-temperature operation of Ga0.47In0.53As/AI0.48In0.52As resonant tunnelling diodes

The first room-temperature operation of Ga0.47In0.53As/Al0.48In0.52As resonant tunnelling (RT) diodes is reported. The peak/valley ratio of the current is as high as 4:1 at room temperature and is 15:1 at 80 K. These are the highest values of peak/valley ratio at the respective temperatures, reported so far, in this material system. The position of the peak in the current/voltage characteristic also showed good agreement with that obtained from an electron tunnelling transmission calculation.     

547-GHz f/sub t/ In/sub 0.7/Ga/sub 0.3/As-In/sub 0.52/Al/sub 0.48/As HEMTs with reduced source and drain resistance

We fabricated 30-nm gate pseudomorphic channel In/sub 0.7/Ga/sub 0.3/As-In/sub 0.52/Al/sub 0.48/As high electron mobility transistors (HEMTs) with reduced source and drain parasitic resistances. A multilayer cap structure consisting of Si highly doped n/sup +/-InGaAs and n/sup +/-InP layers was used to reduce these resistances while enabling reproducible 30-nm gate process. The HEMTs also had a laterally scaled gate-recess that effectively enhanced electron velocity, and an adequately long gate-channel distance of 12nm to suppress gate leakage current. The transconductance (g/sub m/) reached 1.5 S/mm, and the off-state breakdown voltage (BV/sub gd/) defined at a gate current of -1 mA/mm was -3.0 V. An extremely high current gain cutoff frequency (f/sub t/) of 547 GHz and a simultaneous maximum oscillation frequency (f/sub max/) of 400 GHz were achieved: the best performance yet reported for any transistor.     

Al/sub 0.3/Ga/sub 0.7/As/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) doped-channel field-effect transistors (DCFET's)

The properties of both lattice-matched and strained doped-channel field-effect transistors (DCFET's) have been investigated in AlGaAs/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) heterostructures with various indium mole fractions. Through electrical characterization of grown layers in conjunction with the dc and microwave device characteristics, we observed that the introduction of a 150-/spl Aring/ thick strained In/sub 0.15/Ga/sub 0.85/As channel can enhance device performance, compared to the lattice-matched one. However, a degradation of device performance was observed for larger indium mole fractions, up to x=0.25, which is associated with strain relaxation in this highly strained channel. DCFET's also preserved a more reliable performance after biased-stress testings.<>     

High Performance (fT~500GHZ) In0.52Al0.48As/In0.53Ga0.47As/InP Quantum Wire MODFETs Employing Asymmetric Coupled-Well Channels

A coupled-well InAlAs/InGaAs quantum wire MODFET structure is proposed, for which simulations predict improved frequency performance (>500 GHz), over a wider range of V_g, as compared to well/wire devices with a standard MODFET heterointerface. A comparison of several transverse potential well profiles, obtained by varying the placement of a thin barrier within a 100 Å finite well, is presented. In all cases, the quantum wires consist of a 0.1 μm long channel and a 150 Å finite-square-well lateral profile. It has been found that the peak of the electron distribution for the first confined state, as measured from the heterointerface, changes dramatically depending on the location of the thin barrier. For quantum wire structures, realized in the lattice matched system of In_0.52Al_0.48As/In_0.53Ga_0.47As/InP, a change in the barrier location of 25 Å is accompanied by a shift in the carrier peak of more than 40 Å (~20 Å closer to or farther from the spacer-well interface than in the standard MODFET profile). Implications of this are reflected in the current-voltage characteristics (I_d-V_d) and frequency responses (f_T-V_g) of the proposed structures.     

Dependence of electron mobility on spacer thickness and electron density in modulation-doped Ga0.47In0.53As/Al0.48In0.52As heterojunctions

Modulation-doped Ga0.47In0.53As/Al0.48In0.52As heterojunctions were grown by molecular beam epitaxy. Electron mobilities were measured at room temperature and 77 K as a function of undoped Al0.48In0.52As spacer layer thickness and sheet carrier concentration. Enhanced mobilities were as high as 10 900 cm2V?1s?1 at room temperature and 55 500 cm2V?1s?1 at 77 K in these samples with sheet carrier concentrations at 1 33 × 1012 cm?2 (room temperature) and 1.26 × 1012 cm?12 (77 K).