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Proceedings Paper

High Electron Mobility Transistors For Millimeter Wave And High Speed Digital IC Applications
Author(s): Aditya K. Gupta; J. A. Higgins; Chien-Ping Lee
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Paper Abstract

High Electron Mobility Transistors (HEMTs) are currently regarded as the most promising three-terminal devices for ultra-high-speed digital and monolithic millimeter-wave integrated circuits. In their most basic form, these devices consist of a GaAs-MESFET-like FET fabricated on a (A1,Ga)As/GaAs epitaxial layer. The (A1,Ga)As layer is highly doped n-type and the GaAs layer is undoped. Due to the lower electron affinity of (A1,Ga)As, free electrons diffuse out of the doped layer into undoped GaAs where they form a two-dimensional electron gas near the heterointerface. Since the electrons and ionized donors are spatially separated, ionized impurity scattering is reduced and electron transport properties at the heterointerface are comparable to pure GaAs. FETs fabricated on these hetero-junctions offer many advantages such as (i) a small gate-to-channel separation which leads to extremely high transconductances; (ii) high f due to improved electron transport properties; (iii) a small source resistance; and (ivy a small saturation voltage. The benefits improve substantially upon cooling the device. In a mere seven years, HEMT technology has evolved from simple ring oscillators to circuits of LSI complexity such as 16K SRAMs. The speed performance demonstrated by this relatively immature technology has already surpassed all other semiconductor technologies. Ring oscillator gate delays of 5.8 ps at 77K and 10.2 ps at 300K have been achieved using'0.35 μm gate length devices. In the analog domain, HEMTs are the leaders in low noise and high gain amplification. At room temperatures, devices with a noise figure of 2.4 dB at 62 GHz and fmax > 250 GHz have been demonstrated.

Paper Details

Date Published: 2 February 1988
PDF: 23 pages
Proc. SPIE 0795, Characterization of Very High Speed Semiconductor Devices and Integrated Circuits, (2 February 1988); doi: 10.1117/12.940931
Show Author Affiliations
Aditya K. Gupta, Rockwell International Corporation (United States)
J. A. Higgins, Rockwell International Corporation Science Center (United States)
Chien-Ping Lee, Rockwell International Corporation Science Center (United States)

Published in SPIE Proceedings Vol. 0795:
Characterization of Very High Speed Semiconductor Devices and Integrated Circuits
Ravinder K. Jain, Editor(s)

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