Browsing by Author "Peng, CK"

Now showing 1 - 4 of 4

Characteristics of nonalloyed pseudomorphic high electron mobility transistors using InAs/InxGa1-xAs (x=-> 0) AlyGa1-yAs (y=0 -> 0.3) contact structures
(1997-06-01)
Chen, SS
;
Lin, CC
;
Lan, WH
;
Tu, SL
;
Peng, CK
A molecular beam epitaxy InAs/InxGa1-xAs (x = 1 --> 0)/AlyGa1-yAs (y = 0 --> 0.3) heterojunction was used as an ohmic contact structure to the GaAs-based pseudomorphic high electron mobility transistors (PHEMTs). This nonalloyed PHEMT had a specific contact resistance r(c) of 1.05 x 10(-7) Omega . cm(2) and an extrinsic transconductance g(me) of 272 mS/mm for devices with 1 mu m gate-length, microwave measurements shelved a current gain cut-off frequency f(t) of 22 GHz and a maximum oscillation frequency f(max) of 43 GHz. These results are comparable to our best conventional PHEMTs' alloyed at 450 degrees C and 2 min duration. Meanwhile, a small-signal equivalent circuit model of the nonalloyed PHEMT has also been demonstrated.
Characteristics of nonalloyed pseudomorphic high electron mobility transistors using InAs/InxGa1-xAs (x=-> 0) AlyGa1-yAs (y=0 -> 0.3) contact structures
(1997-06-01)
Chen, SS
;
Lin, CC
;
Lan, WH
;
Tu, SL
;
Peng, CK
A molecular beam epitaxy InAs/InxGa1-xAs (x = 1 --> 0)/AlyGa1-yAs (y = 0 --> 0.3) heterojunction was used as an ohmic contact structure to the GaAs-based pseudomorphic high electron mobility transistors (PHEMTs). This nonalloyed PHEMT had a specific contact resistance r(c) of 1.05 x 10(-7) Omega . cm(2) and an extrinsic transconductance g(me) of 272 mS/mm for devices with 1 mu m gate-length, microwave measurements shelved a current gain cut-off frequency f(t) of 22 GHz and a maximum oscillation frequency f(max) of 43 GHz. These results are comparable to our best conventional PHEMTs' alloyed at 450 degrees C and 2 min duration. Meanwhile, a small-signal equivalent circuit model of the nonalloyed PHEMT has also been demonstrated.
High performance non-alloyed pseudomorphic high electron mobility transistors
(1996-07-01)
Peng, CK
;
Lan, WH
;
Tu, SL
;
Yang, SJ
;
Chen, SS
We have studied the InAs/GaAs strained layer superlattice (SLS) structures as non-alloyed contacts applied to pseudomorphic high electron mobility transistors (PHEMTs) grown by the molecular beam epitaxy (MBE) system. Transmission line measurements with four point configurations showed that specific contact resistances between 6.6 x 10(-7) and 2.6 x 10(-6) Omega cm(2) were obtained for the as-grown devices, with a linear correlation coefficient of 0.997. D.c. measurements of the as-grown PHEMT with 1 mu m gate showed a transconductance of 240 ms mm(-1). Microwave measurements on the same device showed a cut-off frequency of 19 GHz and a maximum power gain frequency of 42 GHz. These results are comparable with those of devices with the conventional contact scheme. Meanwhile, since the non-alloying process maintains excellent surface morphology and sharp metal pad edges, AuGeNi type metals can be used in small dimension devices. In contrast, the conventionally alloyed devices showed rough surface morphology and zigzag edges, which may affect device processing and limit the usefulness of AuGeNi metal as the ohmic contact in small dimension devices.
Molecular beam epitaxy regrowth and device performance of GaAs-based pseudomorphic high electron mobility transistors using a thin indium passivation layer
(2000-08-01)
Chen, SS
;
Lin, CC
;
Peng, CK
;
Chan, YJ
;
材料科學與工程學系
Using the technique of molecular beam epitaxy, an indium passivation layer as thin as several tens of Angstrom was implemented to protect underlying III-V epilayers from carbon and oxygen contamination. After the subsequent desorption of the passivation layer, GaAs-based pseudomorphic high electron mobility transistors (PHEMTs) were regrown. Negligible residual carriers were detected at the interface between the regrown PHEMTs and the underlying layer, resulting in a superior performance. The regrown PHEMTs with a 1 x 100 mum(2) gate demonstrated an extrinsic transconductance g(me) as high as 330 mS mm(-) (1). Microwave measurements showed that the current gain cut-off frequency f(t) was 26.5 GHz and the maximum oscillation frequency f(max) was up to 48 GHz. A small-signal equivalent circuit model of the regrown PHEMTs was also evaluated. (C) 2000 Kluwer Academic Publishers.