Search

An AlGaInP multi-quantum-well (MQW) light-emitting diode (LED) with a direct Ohmic contact structure, formed by an indium-tin-oxide (ITO) transparent film and AuBe diffused thin layer, is fabricated and studied. By the deposition of an AuBe metallic thin layer on the surface of Mg-doped GaP window layer, followed by a thermal activation process, a direct Ohmic contact between ITO and p-GaP layers can be obtained. Experimentally, under an injection current of 20 mA, a dynamic resistance of 5.7Ω and a forward voltage of 1.91 V, are obtained. In addition, a higher external quantum efficiency of 9.7% and a larger maximum light output power of 26.6 mW are found for the studied LED. As compared with the conventional LED without this structure, the external quantum efficiency of the studied device is increased by 26% under the injection current of 100 mA. This is mainly attributed to the reduced series resistance resulted from the relatively uniform distribution of AuBe atoms near the GaP layer surface and the effective current spreading ability by the use of ITO film. Moreover, the life behavior is not degraded by using this AuBe diffused layer for the studied LED under a 20 mA operation condition. [ABSTRACT FROM AUTHOR]

A comprehensive study of emitter-ledge thickness of InGaP/GaAs heterojunction bipolar transistors (HBTs) has been undertaken. It is shown that the recombination rate and electron densities are drastically increased near the exposed base surface between the base contact and the emitter ledge. In contrast, the corresponding hole densities are decreased. If the emitter ledge is too thick, current will flow through the undepleted ledge, which increases the emitter-size effect. In contrast, if the emitter ledge is too thin, it may not effectively passivate the surface. Therefore, the thickness of the emitter ledge is a crucial issue and should be carefully considered. It is shown that, from simulated and experimental results, the optimum emitter-ledge thickness of InGaP/GaAs HBT is 100–200 Å. [ABSTRACT FROM AUTHOR]

The temperature-dependent characteristics of an InGaP/InGaAs/GaAs heterostructure field-effect transistor (HFET), using the (NH4)2Sx solution to form the InGaP surface passivation, are studied and demonstrated. The sulfur-passivated device shows significantly improved dc and RF performances over a wide temperature range (300-510 K). With a 1×100-μm2 gate-dimension HFET by (NH4)2Sx treatment, the considerably improved thermal stability over dc performances including lower temperature variation coefficients on the turn-on voltage (-1.23 mV/K), the gate-drain breakdown voltage (-0.05 mV/K), the gate leakage current (1.04 μA/mm·K), the threshold voltage (-1.139 mV/K), and the drain-saturation-current operating regimes (-3.11×10-4/K) are obtained as the temperature is increased from 300 to 510 K. In addition, for RF characteristics, the sulfur-passivated device also shows a low degradation rate on drain-saturation-current operating regimes (-3.29×10-4/K) as the temperature is increased from 300 to 400 K. These advantages provide the promise for high-speed high-frequency high-temperature electronics applications. [ABSTRACT FROM PUBLISHER]

The influences of (NH4)2Sx treatment on an AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor (PHEMT) are studied and demonstrated. Upon the sulfur passivation, the studied device exhibits better temperature-dependent dc and microwave characteristics. Experimentally, for a 1 × 100 μm² gate/dimension PHEMT with sulfur passivation, the higher gate/drain breakdown voltage of 36.4 (21.5) V, higher turn-on voltage of 0.994(0.69) V, lower gate leakage current of 0.6 (571) μA/mm at VGD = -22 V, improved threshold voltage of -1.62 (-1.71) V, higher maximum transconductance of 240 (211) mS/mm with 348 (242) mA/mm broad operating regime (> 0.9gm,max), and lower output conductance of 0.51 (0.53) mS/mm are obtained, respectively, at 300 (510) K. The corresponding unity current gain cutoff frequency fT (maximum oscillation frequency fmax) are 22.2 (87.9) and 19.5 (59.3) GHz at 250 and 400 K, respectively, with considerably broad operating regimes (> 0.8fT, fmax) larger than 455 mA/mm. Moreover, the relatively lower variations of device performances over wide temperature range (300 ∼ 510 K) are observed. [ABSTRACT FROM AUTHOR]

The dc performances of a novel InP-InGaAs tunneling emitter bipolar transistor (TEBT) are studied and demonstrated. The studied device can be operated under an extremely wide collector current regime larger than 11 decades in magnitude (10[sup -12] to 10[sup -1] A). A current gain of 3 is obtained even operated at an ultralow collector current of 3.9 × 10[sup -12] A (1.56 × 10[sup -7] A/cm²). The common-emitter and common-base breakdown voltages of the studied device are higher than 2 and 5 V, respectively. Furthermore, a very low collector-emitter offset voltage of 40 mV is found. The temperature-dependent dc characteristics of the TEBT are measured and studied. Consequentially, based on experimental results, the studied device provides the promise for low-power electronics applications. [ABSTRACT FROM AUTHOR]

Investigates the performance of several III-V compound semiconductor devices. Significance of higher temperature tolerance in semiconductor devices; List of their weakpoints with regards to temperature increase.

Provides information on a study that developed a field-effect transistor using a high-barrier InGaP/GaAs/InGaAs camel-like gate. Discussion on the effect of the applied gate voltage on the barrier height for a homojunction camel-diode; Methodology; Results and discussion.

Abstract-An interesting AIGaInP multiple-quantum-well light-emitting diode (LED) with a direct ohmic contact structure, formed by an indium-tin-oxide (ITO) transparent film and AuBe diffused thin layer, is fabricated and studied. The direct ohmic contact structure is performed by the deposition of an AuBe diffused thin layer and the following activation process on the surface of a Mg-doped GaP window layer. Experimental results demonstrate that a dynamic resistance of 5.71Ω and a forward voltage of 1.91 V, under an injection current of 20 mA, are obtained. In addition, the studied LED exhibits a higher external quantum efficiency of 9.7% and a larger maximum light-output power of 26.6 mW. The external quantum efficiency is increased by 26% under the injection current of 100 mA, as compared with the conventional LED without this structure. This is mainly attributed to the reduced series resistance resulted from the relatively uniform distribution of AuBe atoms near the GaP layer surface and the effective current spreading ability by the use of ITO film. Moreover, the life behavior of the studied LED, under a 20-mA operation condition, is comparable to the conventional LED without this structure. [ABSTRACT FROM AUTHOR]

A new AlGaInP multiple quantum-well light-emitting diode (LED) with a thin carbon-doped GaP contact layer and a transparent conducting indium tin oxide film is fabricated and studied. For comparison, the LEDs with different contact layer structures are also included in this work. Experimental results indicate that the LED with a carbon-doped GaP contact layer exhibits a higher output power of 31.4 mW and a higher external quantum efficiency of 9%. The light-output power, under dc 20-mA operation, of this LED is increased by a factor of 18% as compared with that of conventional LEDs. These results are mainly attributed to the significantly lower series resistance and lower optical absorption effect. Moreover, the new device shows the reduced wavelength shift with 1.7-nm variation between 10 and 200 mA in electroluminescence spectrum. [ABSTRACT FROM PUBLISHER]