Semi-insulating GaAs surface modifications and their influence in the response of THz devices

• Main Authors: A.L. Muñoz-Rosas, N. Qureshi, G. Paz-Martínez, C.G. Treviño-Palacios, J.C. Alonso-Huitrón, A. Rodríguez-Gómez
• Format: Article
• Language: English
• Published: Elsevier 2021-05-01
• Series: Results in Physics
• Subjects: MACE technique; GaAs nanostructuration; Photoconductive antennas; THz emission
• Online Access: http://www.sciencedirect.com/science/article/pii/S2211379721002527

In this work, we use the Metal-Assisted Chemical Etching (MACE) technique together with an NH3 plasma treatment using a Remote Plasma-Enhanced Chemical Vapor Deposition (RPECVD) equipment to modify the surface of semi-insulating GaAs (SI-GaAs) substrates. Using our modified SI-GaAs, we fabricate photoconductive antennas for THz emission to study the modification's influence on the optical and electrical antenna response. We found substantial gaps in the frequency-domain spectra of the devices, whose origin could reside in a change of the substrate's optical absorption due to: (a) a surficial chemical change or (b) a substrate topographic modification or a combination of both. We showed experimentally that slight and reproducible substrate surface modifications could lead to significant variations in the electrical behavior and THz response of SI-GaAs devices.