InP DHBT Analytical Modeling: Toward THz Transistors

Abstract

InP double heterojunction bipolar transistors (InP DHBT) are one of the key technologies considered for terahertz applications. Improvement of their frequency performance is challenging and strongly dependent on various parameters (manufacturing process, geometry, epitaxial structure). In this article, a novel method is developed to take into account these parameters and predict the frequency performance of the technology. This approach consists of rebuilding the S-parameter matrix of the small-signal model. Elements of the small signal model are identified, and their assessment is described in detail. Once calibrated with the present state-of-the-art device features, the model shows a good agreement with the measurements. Based on this result, analysis of the emitter and base technological features are performed along with optimizations of the vertical structure. Finally, the necessary optimizations for developing a terahertz transistor are detailed. This works provides guidelines for technological improvement and opens the way for designing transistors operating at frequencies above a terahertz.

InP DHBT On-Wafer RF Characterization and Small-Signal Modelling up to 220 GHz

“…Extracted parameters behave as expected: RBi and CBCi values decrease with the current. Moreover the value of the emitter resistance RE, the collector resistance RC, the extrinsic basecollector capacitance CBCx, and the base-emitter capacitance CBE are really close to their theoretical values [11]: RE, th = 3.3 Ω, RC, th = 1.6 Ω, CBCx, th = 6.2 fF, and CBE, th = 19 fF. The comparison between the measured and simulated Sparameters is plotted in Fig.…”