Abstract :
Over the past ten years, high electron mobility transistors (HEMTs) consisting of an InAlAs-InGaAs modulation-doped structure on an InP substrate have grown rapidly, not only as the highest speed-potential three-terminal devices but as excellent uniform devices that can be applied to a wide variety of ICs for microwave, millimeter-wave, and lightwave communication systems. In our HEMT structure, the electron channel is formed with a 15 nm thick InGaAs layer beneath a T-shaped gate with a 0.1 μm footprint. A novel InP gate-recess-etch stopper inserted into the InAlAs barrier layer dramatically improves the uniformity of transistor performance (average threshold voltage of -0.65 V has a standard deviation of <40 mV in a 3" wafer), which is essential for large-scale integration of digital logic circuits. The average transconductance, f/sub T/, and f/sub max/ are 1050 mS/mm, 195 GHz, and 230 GHz, respectively. In the last three years, 40 Gbit/s class lightwave communication ICs have been developed using InP-based HEMTs. The fabricated IC chips (2:1 time-division multiplexer IC, baseband amplifier IC, decision IC, 1/2 frequency divider IC, 1:2 demultiplexer, and exclusive-OR) offer practical speed performance beyond 40 Gbit/s with good yield.
Keywords :
HEMT integrated circuits; III-V semiconductors; amplifiers; decision circuits; demultiplexing equipment; frequency dividers; indium compounds; multiplexing equipment; optical receivers; optical transmitters; time division multiplexing; -0.65 V; 0.1 micron; 15 nm; 195 GHz; 230 GHz; 3 in; 40 Gbit/s; HEMT structure; IC yield; InAlAs barrier layer; InAlAs-InGaAs modulation-doped structure; InGaAs layer; InGaAs-InAlAs-InP-InAlAs-InGaAs-InAlAs-InP; InP; InP gate-recess-etch stopper; InP substrate; InP-based HEMT IC technology; InP-based HEMTs; T-shaped gate; average threshold voltage; baseband amplifier IC; decision IC; demultiplexer; digital logic circuits; electron channel; exclusive-OR; frequency divider IC; high electron mobility transistors; large-scale integration; lightwave communication ICs; lightwave communication systems; optical receiver; optical transmitter; time-division multiplexer IC; transconductance; transistor performance uniformity; Electrons; Epitaxial layers; HEMTs; Indium gallium arsenide; Indium phosphide; MODFETs; Microwave devices; Millimeter wave communication; Millimeter wave technology; Millimeter wave transistors;
