Effects of self-heating on planar heterostructure barrier varactor diodes

Abstract

The conversion efficiency for planar Al0:7GaAs/ GaAs heterostructure barrier varactor triplers is shown to be reduced from a theoretical efficiency of 10% to 3% due to selfheating. The reduction is in accordance with measurements on planar Al0:7GaAs/GaAs heterostructure barrier varactor (HBV) triplers to 261 GHz at room temperature and with low temperature tripler measurements to 255 GHz. The delivered maximum output power at 261 GHz is 2.0 mW. Future HBV designs should carefully consider and reduce the device thermal resistance and parasitic series resistance. Optimization of the RF circuit for a 10-m diameter device yielded a delivered output power of 3.6 mW (2.5% conversion efficiency) at 234 GHz.

Microtechnologies for the monolithic fabrication of mm and submm non linear devices

“…A number of solutions exist notably by reducing as far as possible the dimensions of the chips by dicing and lapping. At the moment, the nominal chip dimensions are ~200x100x50 µm 3 and further shrinking of these dimensions becomes troublesome. On the basis of these considerations, we have recently demonstrated the possibility to lift-off the devices and to report the epilayer material such as that shown in Fig.…”

“…From the solid state device side, three terminal devices have exhibited impressive cut-off frequencies up to 1 THz for a Heterostructure Bipolar Transistor, which was transferred onto a copper substrate [1] whereas maximum frequency of oscillation close to 600 GHz was demonstrated for Heterostructure Field Effect Transistors using a deep submicron gate technology and highly strained heteroepitaxy [2]. For two terminal devices, Heterostructure Barrier Varactors (HBV) have shown significant power generation in the 200-300 GHz frequency range [3]- [4] when used as harmonic multipliers and Schottky diodes [5] have demonstrated unrivalled mixing performances up to 2.5 THz [6]. Both devices have their intrinsic cut-off frequency far in the Terahertz frequency range.…”

An electro-thermal HBV model

“…In order to verify the electro-thermal model, we use a well-characterized GaAs-based HBV, UVA-NRL-1174, thoroughly described in [7]. For this device, the series resistance can be approximated by…”

“…With conversion efficiencies in the best case around 20%, most of the pump power is dissipated in the device, causing very high peak temperatures in the active layers. High temperatures can cause material degradation leading to device failure, and also impair the multiplier performance even for low power levels [7], [8]. Therefore, thermal considerations are important for the design of layer structures and device geometries for HBVs.…”

Carrier conduction through the quantum barrier region in a heterostructure barrier varactor induced by an ac bias

“…The central high barrier minimizes the carrier transport through the structure. The conduction current must be as low as possible in order to achieve a high multiplier conversion efficiency [3]. This conduction current has been extensively analyzed for HBVs with a dc bias (see, e.g.…”