Gunn or Transferred‐Electron Devices

Abstract

Transferred‐electron devices are the only microwave devices whose operation is solely based on the bulk‐material properties of semiconductors such as GaAs or InP. These devices are mainly employed in low‐noise medium‐power oscillators up to high millimeter‐wave frequencies. James B. Gunn was the first scientist to observe the underlying physical phenomenon in an experiment and, therefore, these devices are often referred to as Gunn devices. This chapter describes the principles of operation, basic fabrication technologies, and common oscillator circuits for them. Different device structures for performance optimization, optimization procedures, and simulation tools are discussed. The chapter also summarizes the current state of the art of Gunn devices and the outlook covers the prospects of more recent device structures and material systems.

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“…However, Gunn devices have long been known for their efficient operation in a second-harmonic mode [25]. Many commercially available millimeter-wave oscillators with Gunn devices utilize this second-harmonic mode, typically above 60 GHz [25].…”

“…However, Gunn devices have long been known for their efficient operation in a second-harmonic mode [25]. Many commercially available millimeter-wave oscillators with Gunn devices utilize this second-harmonic mode, typically above 60 GHz [25]. More recently, oscillators based on three-terminal devices, such as Si CMOS or SiGe heterojunction bipolar transistors (HBT), have also exploited extraction of harmonic signals to extend the useful frequency range of a particular technology [26]- [29].…”

“…One example is an oscillator at 480 GHz with an InP Gunn device [24], [25]. More recent experiments show that such third-harmonic power extraction from InP Gunn devices is feasible above 500 GHz [25]. These oscillators were also tested for their spectral purity using the same Rohde & Schwartz spectrum analyzer FSU46 as before.…”

“…Favorable material parameters, for example, are higher critical electric fields for avalanche breakdown, higher thermal conductivities, higher permissible operating temperatures, and expected higher carrier drift velocities [25]. However, high threshold electric fields and consequently higher dc bias voltages may result in severe thermal limitations of the device performance [31], [32].…”

“…Although no RF oscillations have been observed to date, bias oscillations were reported [33] and are an indication of the onset of NDR in such GaN Gunn device structures. Furthermore, major improvements in material quality or availability and in fabrication technologies are needed before devices for system applications can be developed [25].…”