D-band (110–170 GHz) InP gunn devices

Abstract

This paper reports on the development of InP Gunn sources for operation in the D-band (li0-170GHz). n+-n-n + structures with flat doping as well as graded doping profiles have been considered. Oscillations were obtained at 108.3 GHz from a 1 #m structure with a uniform n doping of 2.5 x 1016cm-3. The CW RF output power was 33 roW. A 1 #m graded structure with an n doping increasing linearly from 7.5 x 10 ~5 to 2.0 x 10~6cm-3 has resulted in 20roW at 120GHz and 10roW at 136 GHz. These results are believed to correspond to a fundamental mode operation and represent the state-of-the-art performance from InP Gunn devices at these frequencies. This improvement in performance is attributed in part to a processing technique based on the use of etch-stop layers and lnGaAs cap layers. An etch-stop layer allows low-profile mesas (2-3/~m) and InGaAs cap layers help reduce the contact resistance, thus minimizing series resistances in the device. In addition, a physical model based on the Monte Carlo method was developed to aid in the design of structures for high frequency operation. Experimental results obtained from a 1.7#m Gunn device operating at W-band frequencies were used to estimate appropriate InP material parameters.

Submillimeter-Wave InP Gunn Devices

“…This improvement is attributed to the enhanced electric field near the cathode and the corresponding faster transfer of electrons to higher energy valleys [5]. The doping profile of Fig.…”

“…8 was developed during the studies of -band Gunn devices in the fundamental mode [5]. To gain confidence in its predictions at high millimeter-and submillimeter-wave frequencies, the results from this program were first compared with experimental data at lower millimeter-wave frequencies, in particular at -band [29].…”

“…2(a), was designed for fundamental-mode operation at -band frequencies [5], [6]. As can be seen from Fig.…”

“…1, under continuous-wave (CW) operation, experimental data over a wide frequency range appeared to confirm those early predictions. However, recent theoretical and experimental work on fundamental-mode operation at -band (110-170 GHz) frequencies [5], [6] indicated that optimized device structures and much improved heat dissipation extend the operation of Gunn devices, in particular, of InP devices, to much higher frequencies. These studies also identified RF power extraction at the second or higher harmonic frequencies as a very efficient method of reaching submillimeter-wave frequencies [7], [8].…”

Two‐terminal InGaAs microwave amplifier

“…As such, the heating effect rapidly escalates in short channels, which may easily lead to breakdown. A number of unusual techniques have to be utilized to overcome this issue, including thinning the substrate down to 2 μm and mounting chips on diamond heat sinks, and yet, to the best of our knowledge, the highest fundamental oscillation frequency of InP vertical Gunn diodes is only 160 GHz to date . ‐ …”