Principles and Technology of Modulation Doped Field Effect Transistors

Since the invention of the transistor, there has been a great deal of activity and progress in semiconductor technology and understanding, particularly in new heterostructures and superlattices as well as devices based on them.

With the development of high quality SiO2 on Si having low interface state densities, MOSFET devices relying on the high mobility two dimensional electron became available in the 1960s and represent the workhorse of integrated circuits today. Two-dimensional electron gas, similar to that in MOSFETs, can also be obtained at GaAs/AlGaAs interfaces which provides even higher mobility, higher velocity and a lattice matched interface.

MOSFET-like devices, called MODFETs, have already achieved switching speeds of about 5 Ps at 77K, current gain cut-off frequencies of about 250 GHz and maximum oscillation frequencies of about 400 GHz.

In addition to GaAs/AIGaAs on GaAs, the strained system of InGaAs/AIGaAs on GaAs and the InGaAs/InAlAs system on InP substrates have been investigated.

In fact, the InP system, at the time of this writing, held the milimeter wave fT current gain cut-off frequency record and yielded extremely low-noise operation, 1dB at 60 Ghz for 0.2 mu gate lengths. In this book, fundamentals, technology and performance of MODFETs, both as microwave and digital devices, are treated in detail.

In addition, introductory material particularly that dealing with semiconductor and heterojunction physics, where applicable, is also provided.

The book is arranged into two volumes with a total of nine chapters.

Volume 1 contains Chapters 1 to 5, and Volume 2 covers Chapters 6 to 9. In Volume 2, Chapter 6 is devoted mainly to the experimental and technological aspects of two dimensional transport.

Chapter 7 treats the two dimensional electron gas properties under the influence of external field, such as that found in MODFETs.

Chapter 8 covers the particulars of MODFETs with respect to microwave/millimeter wave performance issues.

Models for noise and equivalent circuit parameters as well as the performance of various MODFETs are discussed.

Finally, Chapter 9 makes an attempt to cover the ever-evolving digital performance of MODFETs.

Unlike the microwave/millimeter wave area, the choice of device for digital applications is not very clear and often application dependent.

As a result, a great deal of effort is expended to compare MODFETs with other devices in several key application area along with projections.

The data included in Chapters 8 and 9 are those obtained up to the middle of 1989.