High frequency doubling efficiency THz GaAs Schottky barrier diode based on inverted trapezoidal epitaxial cross-section structure

A high-performance terahertz Schottky barrier diode(SBD)with an inverted trapezoidal epitaxial cross-sectional structure featuring high varactor characteristics and reverse breakdown characteristics is reported in this paper.Inductively coupled plasma dry etching and dissolution wet etching are used to define the profile of the epitaxial layer,by which the voltage-dependent variation trend of the thickness of the metal-semiconductor contact depletion layer is modified.The simulation of the inverted trapezoidal epitaxial cross-section SBD is also conducted to explain the physical mechanism of the electric field and space charge region area.Compared with the normal structure,the grading coefficient M increases from 0.47 to 0.52,and the capacitance modulation ratio(C^(max)/C_(min))increases from 6.70 to 7.61.The inverted trapezoidal epitaxial cross-section structure is a promising approach to improve the variable-capacity ratio by eliminating the accumulation of charge at the Schottky electrode edge.A 190 GHz frequency doubler based on the inverted trapezoidal epitaxial cross-section SBD also shows a doubling efficiency of 35%compared to that 30%of a normal SBD.

A terahertz on-chip InP-based power combiner designed using coupled-grounded coplanar waveguide lines

This article presents the design and performance of a terahertz on-chip coupled-grounded coplanar waveguide(GCPW)power combiner using a 50μm-thick InP process.The proposed topology uses two coupled-GCPW lines at the end of the input port to substitute two quarter-wavelength GCPW lines,which is different from the conventional Wilkinson power combiner and can availably minimize the coverage area.According to the results obtained,for the frequency range of 210-250 GHz,the insertion losses for each two-way combiner and four-way combiner were lower than 1.05 dB and1.35 dB,respectively,and the in-band return losses were better than 11 dB.Moreover,the proposed on-chip GCPW-based combiners achieved a compromise in low-loss,broadband,and small-size,which can find wide applications in terahertz bands,such as power amplifiers and signal distribution networks.