N. Yokoyama et al., RESONANT-TUNNELING HOT-ELECTRON TRANSISTORS - PRESENT STATUS AND FUTURE-PROSPECTS, Philosophical transactions-Royal Society of London. Physical sciences and engineering, 354(1717), 1996, pp. 2399-2411
We proposed and demonstrated a resonant-tunnelling hot electron transi
stor (RHET) in 1985, and developed a multi-emitter RHET in 1993, enabl
ing us to make an SRAM cell and multi-input logic gates using a single
transistor. Through the development of these quantum tunnelling trans
istors, we have created the technology needed to fabricate precisely c
ontrolled quantum well structures, and have mostly understood the phys
ics behind quantum well structures. Although this technology has been
successfully used to develop heterostructure transistors and quantum w
ell laser diodes, RHETs cannot yet be used in practical applications.
One reason is that the RHET should be cooled down to about 77 K and it
s functionality is insufficient to replace conventional semiconductor
devices. To make these RHETs practical for future use in cryoelectroni
c systems, integration with complementary-HEMT logic circuits or devel
opement of new architecture circuits will be essential. There are also
other important areas of research for us. One is to develop room temp
erature quantum functional bipolar transistors. Another is to develop
quantum box devices based on the RHET technology, searching ultrasmall
limit of electron devices. These research will be also useful in the
development of photonic devices, such as quantum dot lasers and new ph
otonic memory devices.