HEMT´s and New Devices for High-Speed Applications

This paper describes the state of the art in the research and development of HEMT´s and new devices for microwave-frequency and high-speed applications in Japan. Low-noise HEMT´s have already been commercial available, and are successfully utilized in the application such as satellite-communications and radio astronomy. A 4.1K HEMT gate array was fabricated, which was the largest scale HEMT logic LSI. This gate array realized a 16 × 16 bit parallel multiplier which exhibited the multiplication-time of 4.1 ns at 300 K. A new functional, resonant-tunneling hot electron transistor (RHET) was demonstrated, which enables us to build an Exclusive-NOR gate using only one transistor. A HBT with a modified collector structure in which electron transport can mostly be confined to ¿-valley of GaAs was developed, and the HBT achieved the maximum fT as high as 105 GHz at a collector current density in the mid 104 A/cm2.