Since the first bipolar transistor was investigated in 1947, enormous efforts have been devoted to semiconductor devices. The strong world­ wide competition in fabricating metal-oxide-semiconductor field-effect of develop­ transistor (MOSFET) memories has accelerated the pace ments in semiconductor technology. Bipolar transistors play a major role due to their high-speed performance. Delay times of about 20 ps per gate have already been achieved. Because of this rapid technologi­ cal progress, it is difficult to predict the future with any certainty. In 1987 a special session on ultrafast bipolar transistors was held at the European Solid-State Device Research Conference. Its aim was to sum­ marize the most recent developments and to discuss the future of bip­ olar transistors. This book is based on that session but also includes contributions by other participants, such that a broad range of up-to­ is presented. Several conclusions can be drawn from date information this information: the first and most important is the very large poten­ tial for future progress still existing in this field. This progress is char­ acterized by the drive towards higher speed and lower power con­ sumption required for complex single-chip systems, as well as by sev­ eral concrete technological implementations for fulfilling these dem­ is that a large part of this potential can be ands. The second conclusion realized by rather unsophisticated techniques and configurations well suited to uncomplicated transfer to fabrication.