Abstract

This paper investigates fully integrated Terahertz (THz) Schottky detectors using silver (Ag) metallic nanowires (NWs) with 120 nm diameter as bridge contacts for zero-bias operating THz detectors based on highly doped Gallium Arsenide (GaAs) and Indium Gallium Arsenide (InGaAs) layers. The combination of InGaAs and metallic NWs shows improved performance at zero-bias than a GaAs based detector with a simulated capacitance of 0.5 fF and a series resistance of 29.7 $\Omega $ . Thus, the calculated maximum cut-off frequency of 2.6 THz was obtained for a NW contacted vertical InGaAs THz detector. Initial THz measurements were carried out using a common THz setup for frequencies up to 1.2 THz. A responsivity of 0.81 A/W and a low noise-equivalent power (NEP) value of 7 pW/ $ {~\sqrt {Hz}}$ at 1 THz were estimated using the measured IV-characteristics of the zero-bias NW-InGaAs based THz Schottky detector.

Highlights

  • T Hz (100 GHz - 10 THz) nanotechnologies represent a new approach to material science and engineering, as well as for design of new devices and processes for the fabrication of compact high-frequency devices

  • In order to investigate the room temperature THz detectors, four detector types were fabricated: Two detectors were based on standard contacts and the other two were based on Ag-NW contacts

  • The vertical NW-Indium Gallium Arsenide (InGaAs) Schottky detector showed much higher zero bias responsivity in comparison to the detector based on NW-Gallium Arsenide (GaAs) and to the standard detectors (SD)

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Summary

INTRODUCTION

T Hz (100 GHz - 10 THz) nanotechnologies represent a new approach to material science and engineering, as well as for design of new devices and processes for the fabrication of compact high-frequency devices. Schottky diodes are still the most sensitive detector concept for direct detection of THz radiation at room temperature. This kind of detector combines a high responsivity with very short response time and compact dimensions. Similar to this approach our metallic nanowires reduce the Schottky barrier height This property and the low capacitance lead to efficient zero-bias operation and low noise THz detection capability. The metallic nanowires were aligned using DEP These THz Schottky detectors based on GaAs and InGaAs were simulated, fabricated and characterised using Ag-NWs with 120 nm diameter as bridge contacts and were compared to standard detectors (SD) fabricated with evaporated finger contacts

SIMULATIONS
FABRICATION AND RESULTS
THZ RESPONSIVITY AND NEP
CONCLUSION
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