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.<>     

MESFET-like transferred-electron devices in In/sub 0.53/Ga/sub 0.47/As

In/sub 0.53/Ga/sub 0.47/As transferred-electron devices with Schottky-gate electrodes were fabricated. These devices can be used in optoelectronic circuits on InP or as millimetre wave oscillators. For the realisation of the gate electrode several enhancement layers were tested to increase the Schottky barrier height on In/sub 0.53/Ga/sub 0.47/As. The triggering of single dipole domains in the device was demonstrated.<>     

Performance improvement in tensile-strained In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As metamorphic HEMT

This paper proposes a In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As (x=0.3-0.5-0.3) metamorphic high-electron mobility transistor with tensile-strained channel. The tensile-strained channel structure exhibits significant improvements in dc and RF characteristics, including extrinsic transconductance, current driving capability, thermal stability, unity-gain cutoff frequency, maximum oscillation frequency, output power, power gain, and power added efficiency.     

Low-temperature MBE-grown In/sub 0.52/Ga/sub 0.18/Al/sub 0.30/As/InP optical waveguides

The MBE growth of In/sub 0.52/Ga/sub 0.18/Al/sub 0.30/As ( lambda /sub g/=1.06 mu m) layers in the temperature range of 400-450 degrees C was demonstrated to give high-quality optical waveguides which not only exhibit low propagation losses as low as 0.5 dB/cm at lambda =1.55 mu m but concomitantly high resistivity of >10/sup 4/ Omega cm. The refractive index of In/sub 0.52/Ga/sub 0.18/Al/sub 0.30/As was estimated to be 3.207+or-0.03 at lambda =1.55 mu m.<>     

Refractive index step and optical confinement in Ga/sub 0.86/In/sub 0.14/As/sub 0.13/Sb/sub 0.87//Ga/sub 0.73/Al/sub 0.27/As/sub 0.02/Sb/sub 0.98/ double heterostructure lasers emitting at 2.2 mu m

Using theoretical fitting to measured transverse far field patterns in Ga/sub 0.86/In/sub 0.14/As/sub 0.13/Sb/sub 0.87//Ga/sub 0.73/Al/sub 0.27/As/sub 0.02/Sb/sub 0.98/ DH lasers emitting at 2.2 mu m the authors estimated the value of the active layer refractive index as 3.78. This value, higher than assumed earlier based on theoretical calculations, ensures good optical confinement for this kind of heterostructure and provides a good theoretical fit with the authors' experimental data of threshold current density against active layer thickness.<>     

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.     

Threshold voltage of submicron Ga/sub 0.47/In/sub 0.53/As HIGFETs

Presents threshold voltage data for Al/sub 0.48/In/sub 0.52/As/Ga/sub 0.47/In/sub 0.53/As/InP heterostructure insulated gate FETs (HIGFETs) with gate lengths from 1.2 mu m to 0.4 mu m. The refractory-gate, self-aligned fabrication process was applied to MBE-grown structures with 300 AA Ga/sub 0.47/In/sub 0.53/As channels and semi-insulating superlattice buffers to achieve sharp pinchoff with excellent threshold uniformity. HIGFETs with L/sub g/=1.2 mu m showed a threshold voltage of -0.076+or-0.019 V, making them well-suited to application in direct-coupled FET logic (DCFL) circuits.<>     

Microwave performance of 0.4 mu m gate metamorphic In/sub 0.29/Al/sub 0.71/As/In/sub 0.3/Ga/sub 0.7/As HEMT on GaAs substrate

MBE grown metamorphic In/sub 0.29/Al/sub 0.71/As/In/sub 0.3/Ga/sub 0.7/As/GaAs high electron mobility transistors (HEMTs) have been successfully fabricated. A 0.4 mu m triangular gate device showed transconductance as high as 700 mS/mm at a current density of 230 mA/mm. The measured f/sub T/ was 45 GHz and f/sub max/ was 115 GHz. These high values are, to the authors knowledge, the first reported for submicrometre metamorphic InAlAs/InGaAs/GaAs HEMTs with an indium content of 30%.<>     

Ultralow leakage In/sub 0.53/Ga/sub 0.47/As p-i-n photodetector grown on linearly graded metamorphic In/sub x/Ga/sub 1-x/P buffered GaAs substrate

A novel top-illuminated In/sub 0.53/Ga/sub 0.47/As p-i-n photodiodes (MM-PINPD) grown on GaAs substrate by using linearly graded metamorphic In/sub x/Ga/sub 1-x/P (x graded from 0.49 to 1) buffer layer is reported. The dark current, optical responsivities, noise equivalent power, and operational bandwidth of the MM-PINPD with aperture diameter of 60 /spl mu/m are 13 pA, 0.6 A/W, 3.4/spl times/10/sup -15/ W/Hz/sup 1/2/, and 7.5 GHz, respectively, at 1550 nm. The performances of the MM-PINPD on GaAs are demonstrated to be comparable to those of a similar device made on InGaAs-InP substrate.     

Device linearity comparison of uniformly doped and /spl delta/-doped In/sub 0.52/Al/sub 0.48/As/In/sub 0.6/Ga/sub 0.4/As metamorphic HEMTs

The uniformly doped and the /spl delta/-doped In/sub 0.52/Al/sub 0.48/As/In/sub 0.6/Ga/sub 0.4/As metamorphic high-electron mobility transistors (MHEMTs) were fabricated, and the dc characteristics and the third-order intercept point (IP3) of these devices were measured and compared. Due to more uniform electron distribution in the quantum-well region, the uniformly doped MHEMT exhibits a flatter transconductance (G/sub m/) versus drain-to-source current (I/sub DS/) curve and much better linearity with higher IP3 and higher IP3-to-P/sub dc/ ratio as compared to the /spl delta/-doped MHEMT, even though the /spl delta/-doped device exhibits higher peak transconductance. As a result, the uniformly doped MHEMT is more suitable for communication systems that require high linearity operation.     

Negative differential resistance of GaAs/Al/sub x/Ga/sub 1-x/As multiquantum well structures under high power photoexcitation: structure optimisation for an oscillator

A study is presented of the photocurrent behaviour of p-i-n diodes having GaAs/Al/sub x/Ga/sub 1-x/As MQW absorption regions for varying incident power, incident wavelength and barrier height, given by the Al fraction x. Optimum results for applications in high power oscillators are expected to be obtained for 0.1>     

Effect of strain on microwave noise characteristics in In/sub 0.52/Al/sub 0.48/As/In/sub x/Ga/sub 1-x/As (0.53

Chough  K.B. Hong  W.-P. Florez  L. Song  J.I. 《Electronics letters》1993,29(15):1338-1340

Metal-semiconductor-metal photodetector on p-type In/sub 0.53/Ga/sub 0.47/As

An MSM Schottky barrier photodetector based on p-type In/sub 0.53/Ga/sub 0.47/As suitable for detection in the 0.8-1.7 wavelength range is reported. Aluminium metallisation was used. The large area devices exhibited responsivity of about 0.4 A/W at 1.3 mu m and tau /sub on/>     

Field dependence of impact ionization coefficients in In/sub 0.53/Ga/sub 0.47/As

Electron and hole ionization coefficients in In/sub 0.53/Ga/sub 0.47/As are deduced from mixed carrier avalanche photomultiplication measurements on a series of p-i-n diode layers, eliminating other effects that can lead to an increase in photocurrent with reverse bias. Low field ionization is observed for electrons but not for holes, resulting in a larger ratio of ionization coefficients, even at moderately high electric fields than previously reported. The measured ionization coefficients are marginally lower than those of GaAs for fields above 250 kVcm/sup -1/, supporting reports of slightly higher avalanche breakdown voltages in In/sub 0.53/Ga/sub 0.47/As than in GaAs p-i-n diodes.     

Low dark current quasi-Schottky barrier MSM-photodiode structures on n-Ga/sub 0.47/In/sub 0.53/As with p/sup +/-Ga/sub 0.47/In/sub 0.53/As cap layer

The p/sup +/-cap layer was used to fabricate a metal-semiconductor-metal (MSM) interdigitated photodetector on Ga/sub 0.47/In/sub 0.53/As. The measured barrier height was Phi /sub Bn=/0.52 V, the ideality factor n=1.1 and average dark current density 2 mA/cm/sup 2/. A rise time of 45 ps at lambda =1.3 mu m under 2 V bias was measured for an MSM photodiode with 3 mu m finger width and finger gaps and an active area of 100*100 mu m/sup 2/.<>     

High transconductance of 2.25 S/mm observed at 16 K for 195-nm-gate In/sub 0.75/Ga/sub 0.25/As/In/sub 0.52/Al/sub 0.48/As HEMT fabricated on [411]A-oriented InP substrate

We achieved a maximum transconductance (g/sub m/) of 2.25 S/mm at 16 K for a 195-nm-gate In/sub 0.75/Ga/sub 0.25/As/In/sub 0.52/Al/sub 0.48/As pseudomorphic high-electron mobility transistor (PHEMT) fabricated on a [411]A-oriented InP substrate, which is the highest value ever reported for HEMTs. This PHEMT also showed a much enhanced cutoff frequency (f/sub T/) of 310 GHz at 16 K, compared with its room temperature value (245 GHz). The significantly enhanced g/sub m/ and f/sub T/ at 16 K can be attributed to the higher saturation velocity in the region "under the gate," which is caused not only by suppressing the phonon scattering, but also by suppressing the interface roughness scattering due to the "(411)A super-flat InGaAs/InAlAs interfaces" (effectively atomically flat heterointerfaces over a wafer-size area).     

Room-temperature self-organised In/sub 0.5/Ga/sub 0.5/As quantum dot laser on silicon

The first room-temperature operation of In/sub 0.5/Ga/sub 0.5/As quantum dot lasers grown directly on Si substrates with a thin (/spl les/2 /spl mu/m) GaAs buffer layer is reported. The devices are characterised by J/sub th//spl sim/1500 A/cm/sup 2/, output power >50 mW, and large T/sub 0/ (244 K) and constant output slope efficiency (/spl ges/0.3 W/A) in the temperature range 5-95/spl deg/C.     

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.     

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.     

alpha factor improvements in high-speed p doped In/sub 0.35/Ga /sub 0.65/As/GaAs MQW lasers

The authors investigate experimentally for the first time the improvements in the linewidth enhancement factor, alpha , resulting from simultaneous addition of strain and p-doping in high-speed GaAs-based multiquantum well lasers. The alpha factor is determined from measured changes in both gain and refractive index as a function of CW bias current, yielding alpha 3.1 and 1.4 at the threshold lasing wavelength for unstrained GaAs/Al/sub 0.25/Ga/sub 0.75/As and p-doped strained In/sub 0.35/Ga/sub 0.65/As/GaAs devices, respectively.<>