Browsing by Author "Huang, RT"

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Comparison of InGaP/InGaAs/GaAs and InGaPtInGaAs/AlGaAs pseudomorphic high electron mobility transistors
(2001-12-01)
Huang, CE
;
Lee, CP
;
Huang, RT
;
Chang, MCF
;
電子工程學系及電子研究所
We have studied the DC and RF characteristics of InGaP/InGaAs/AlGaAs and InGaP/InGaAs/GaAs pseudomorphic high electron mobility transistors (PHEMTs). The InGaP gate barrier provides adequate carrier confinement for the channel carriers and at the same time eliminates the problems associated with AlGaAs. Excellent device performance was obtained for both types of devices. No short channel effect was observed at a gate length as low as 0.3 mum. The InGaP/InGaAs/AlGaAs PHEMTS are superior in that they have higher transconductance, higher current carrying capability and better RF performance. This is attributed to the better carrier confinement at the back channel. These results demonstrate that InGaP/InGaAs/AlGaAs PHEMTs are favorable candidates for microwave applications.
Critical spacing between emitter and base in InGaP heterojunction bipolar transistors (HBTs)
(2002-10-01)
Huang, CE
;
Lee, CP
;
Liang, HC
;
Huang, RT
;
電子工程學系及電子研究所
In this paper, the influence of the spacing between the emitter and the base on the performance of InGaP heterojunction bipolar transistors (HBT) was experimentally studied. We found that the emitter to base spacing can be reduced to as small as 0.6 mum without causing a significant drop in the current gain. The reduction in emitter-to-base spacing, however, leads to improvement in high-frequency performance and device phase noise. For optimal dc, RF, and low-frequency noise performances, we have determined that a critical spacing of 0.6similar to0.8 mum between the emitter and the base of an InGaP HBT is required.
Direct observation of structure effect on ferromagnetism in Zn1-xCoxO nanowires
(2006-06-01)
Jian, WB
;
Wu, ZY
;
Huang, RT
;
Chen, FR
;
Kai, JJ
Diameter-controllable single-crystalline ZnO nanowires (NWs), with the [0001] growth direction in the plane, have been fabricated by using thermal evaporation method. The as-grown NWs with diameters of similar to 40 nm were implanted with various amounts of Co ions. These Zn1-xCoxO (x <= 0.11) NWs possessed a high density of bombardment-induced orientation variations and stacking faults, and exhibited paramagnetic behavior. After thermal annealing, the structural defects largely disappeared and noticeable hysteresis in the magnetization loops were observed, indicating the presence of apparent ferromagnetic ordering in the NWs. This result provides important insight into the role played by defects in relation to the occurrence of ferromagnetism in diluted magnetic semiconductor NWs.