• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.11
• /
• pp.1-8
• /
• 2011

One of the most important parameters that limit maximum output power of transistor is breakdown. InAlAs/InGaAs/GaAs Metamorphic HEMTs (MHEMTs) have some advantages, especially for cost, compared with InP-based ones. However, GaAs-based MHEMTs and InP-based HEMTs are limited by lower breakdown voltage for output power even though they have good microwave and millimeter-wave frequency performance with lower minimum noise figure. In this paper, InAlAs/$In_xGa_{1-x}As$/GaAs MHEMTs are simulated and analyzed for breakdown. The parameters affecting breakdown are investigated in the fabricated 0.1-${\mu}m$ ${\Gamma}$-gate MHEMT device having the modulation-doped $In_{0.52}Al_{0.48}As/In_{0.53}Ga_{0.47}As$ heterostructure on the GaAs wafer using the hydrodynamic transport model of a 2D commercial device simulator. The impact ionization and gate field effect in the fabricated device including deep-level traps are analyzed for breakdown. In addition, Indium mole-fraction-dependent impact ionization rates are proposed empirically for $In_{0.52}Al_{0.48}As/In_xGa_{1-x}As$/GaAs MHEMTs.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.3
• /
• pp.66-74
• /
• 1999

InAlGaAs/InGaAs HBTs with the various emitter junction gradings(xf=0.0-1.0) and the modified collector structures (collector- I;n-p-n, collector-II;i-p-n) are simulated and analyzed by HMC (Hybrid Monte Carlo) method in order to find an optimum structure for the shortest transit time. A minimum base transit time($ au$b) of 0.21ps was obtainsed for HBT with the grading layer, which is parabolically graded from $x_f$=1.0 and xf=0.5 at the emitter-base interface. The minimum collector transit time($\tau$c) of 0.31ps was found when the collector was modified by inserting p-p-n layers, because p layer makes it possible to relax the electric field in the i-type collector layer, confining the electrons in the $\Gamma$-valley during transporting across the collector. Thus InAlGaAs/InGaAs HBT in combination with the emitter grading($x_f$=0.5) and the modified collector-III showed the transit times of 0.87 psec and the cut-off frequency (f$\tau$) of 183 GHz.

• Journal of the Korean Vacuum Society
• /
• v.20 no.5
• /
• pp.345-355
• /
• 2011

GaAs-based metamorphic high electron mobility transistors (MHEMTs) and InP-based high electron mobility transistors (HEMTs) have good microwave and millimeter-wave frequency performance with lower minimum noise figure. MHEMTs have some advantages, especially for cost, compared with InP-based ones. In this paper, InAlAs/InxGa1-xAs/GaAs MHEMTs are simulated for DC/RF small-signal analysis. The hydrodynamic simulation parameters are calibrated to a fabricated 0.1-${\mu}m$ ${\Gamma}$-gate MHEMT device having the modulation-doped $In_{0.52}Al_{0.48}As/In_{0.53}Ga_{0.47}As$ heterostructure on the GaAs substrate, and the simulations for RF small-signal characteristics are performed, compared with the measured data, and analyzed for the devices. In addition, the simulations for the DC/RF characteristics of the MHEMTs with different gate-recess structures are performed, compared and analyzed.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.9 no.2
• /
• pp.91-97
• /
• 2009

The performance of GaInP/GaAs tandem solar cells with AlInP growth temperatures of 680$^{\circ}C$ and 700 $^{\circ}C$ on n-type GaAs (100) substrate with 2$^{\circ}$ and 6$^{\circ}$ tilt angles has been investigated. The series resistance and open circuit voltage of the fabricated tandem solar cells are affected by the substrate tilt angles and the growth temperatures of the window layer when zinc is doped in the tunnel diode. With carbon doping as a p-type doping source in the tunnel diode and the effort of current matching between top and bottom cells, GaInP/GaAs tandem solar cell has been exhibited 25.58% efficiency.

• 제어로봇시스템학회:학술대회논문집
• /
• 1988.10a
• /
• pp.620-626
• /
• 1988

GaAs solar cells may be the most attractive and efficient power source of a satellite. GaAs is more radiation tolerant and less temperature sensitive than widely used silicon. $Al_{x}$ Ga$_{1-x}$ As/GaAs solar cells have been designed and fabricated by Liquid Phase Epitaxial method. GaAs solar cells, of which structure is about 0.2 .mu.m p$^{+}$ - window layer, 0.6-1.O .mu.m Ge-doped p-layer. 3.mu.m n-GaAs layer and n$^{+}$ - buffer layer, have been characterized as a function of operating temperature from 25 .deg.C to 130 .deg.C. Open circuit voltage decreases linearly with increasing temperature by 1.4-1.51 mV/ .deg.C while degradation of silicon solar cells is about 2.2-2.5 mV/ .deg.C, short circuit current does not increase much with increasing temperature. Relative efficiency decreases with increasing of temperature by about 0.21-0.29 %/ .deg.C. Efficiency degradation of silicon solar cells with temperature is known to be about 0.5%/ .deg.C and our results show GaAs solar cells may be an excellent candidate for concentrated solar cells.ells.

• Journal of the Microelectronics and Packaging Society
• /
• v.6 no.1
• /
• pp.1-10
• /
• 1999

InGaP epilayers were grown on the flat, $2^{\circ}$off, $6^{\circ}$ off, and $10^{\circ}$off GaAs substrates by organo-metallic vapor phase epitaxy, and influences of crystallographic misorientation of the substrate on the structural and optical properties such as lattice mismatch, elastic strain, lattice curvature, misfit stress, and PL intensity /line-width were investigated in this study. Material characterizations were carried out by TXRD( tripple-axis x-ray diffractometer) and low temperature (11K) PL (photoluminescence). With increase of the substrate misorientation angle (S.M.A.), the relative incorporation of Ga atoms on the substrate surface was found to be enhanced. Also, with increase of the S. M. A., the x-ray line-width of the InGaP epilayer was reduced, indicating that the crystal quality of the epilayer could be improved tilth a misoriented substrate. It was also found that the elastic accommodation of the strain-free lattice misfit was more remarkable in a misoriented sample. PL intensity increased, and PL line-width and emission wavelength decreased with the increase of S. M. A. The results conclude that the elastic characteristics and the crystal quality of the InGaP epilayer could be remarkably enhanced when the misoriented substrates were employed.

• Korean Journal of Optics and Photonics
• /
• v.12 no.1
• /
• pp.40-47
• /
• 2001

The structural dependence of the performance of an 1.55 $1.55{\mu}m$ InGaAsPIInGaAsP MQW electro-absorption modulator for highspeed digital fiber communication was systematically investigated. The effects of n-doped SCH region length $t_n$ as well as the general structure parameters including quantum well number $N_w$, well-thickness $t_w$, detuning wavelength $\Delta\lambda$, and device length L were thoroughly analyzed. Thereby, a high-pelfoIDlance electro-absorption modulator with device length L of $100{\mu}m$ was successfully designed. The designed structure showed excellent characteristics that have residual loss less than -1.5 dB, operational voltage from 0 V to -2V, and extinction ratios of -2.92 dB at $V_{\alpha}$=-1 V and -10 dB at $V_{\alpha}$=-2V.X>=-2V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.240-240
• /
• 2009

We developed the low level laser therapy(LLLT) apparatus for external injury cure using a GaAsP Diode. This equipment was fabricated by using GaAsP diode and a microcontroller, and designed to enable us to control light irradiation timer, and frequency. In this paper, the designed device was used to find out how GaAsP diode light source affects the skin wound of RAT. In the experiment, $1cm^2$ wounds on the External injury of RAT were made. Light irradiation RAT and none light irradiation RAT divided, each RAT was irradiated 20 min a day for 9 days. In result, compared with none light irradiation RAT, the lower incidence of inflammation and faster recovery was shown in light irradiation RAT.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.1022-1025
• /
• 2002

This paper presents the reliability of planar InP/InGaAs avalanche photodiodes (APD's) with recess etching, which is very crucial for the commercial 10-Gb/s optical receiver application. A versatile design for the planar InP/InGaAs APD's and bias-temperature tests to evaluate long-term reliability at temperature from 200 to $250^{\circ}C$. The reliability is examined by accelerated life tests by monitoring dark current and breakdown voltage. The lifetime of the APD's is estimated by a degradation activation energy. Based on the test results, it is concluded that the planar InP/InGaAs APD's with recess etching shows the sufficient reliability for practical 10-Gb/s optical receivers.

• Proceedings of the IEEK Conference
• /
• 2000.11b
• /
• pp.9-12
• /
• 2000

InP/lnGaAs heterojunciton phototransistors (HPTs) with transparent emitter contacts were fabricated and characterized. Indium Tin Oxide was RF sputtered for the emitter contacts. By comparison with InP/InGaAs HBTs, the dc characteristics of InP/lnGaAs HPTs demonstrated offset voltage due to ITO emitter contacts and similar common emitter current gain. The model parameters were extracted and a simple SPICE simulations were performed.