Au-n-Type GaAs Schottky Barrier and Its Varactor Application

It has lioon demonstrated that under suitable conditions a metal-tosemiconductor rectifying contact may exhibit characteristics predictable from the simple theories advanced by Schottky 1 and Bothe.2 An example of this type of system is the Au-n-type Si Schottky barrier which was reported earlier. 3 In tho present paper evidence is presented to show that Au-n-type GaAs is also such a case. The main features of a metal-to-semiconductor contact are that it may be designed as a majority carrier rectifier, i.e., noninjecting rectifying junction, and that the junction is accurately describable in terms of an ideal step junction. The first feature implies that the frequency response of the diode is limited only by RC charging time or transit time rather than by minority carrier lifetime. High cutoff frequency can be achieved through the use of an epitaxial structure. Such diodes may find application in high-speed switching, microwave detection and mixing, harmonic generation, or parametric amplification using the diode as a varactor. The first of those applications, fast switching, has boon discussed elsewhere.4 215