GaN Lattice Damage and GaN-HEMT Metrology by Cameraless T-Ray Imaging and Time-Domain Spectroscopy

Abstract

Gallium nitride (GaN) film grown on a silicon substrate has been investigated for high electric field-induced lattice damage via cameraless terahertz (T-ray) imaging technique. In addition, T-ray time-domain spectroscopy (TDS) has been conducted on the same GaN film as a function of depth via nondestructive and noncontact pump-probe technique. This is termed as the deep-level TDS. Further, a pair of GaN high electron mobility transistor (HEMT) dies has been imaged at the channel area where the deep-level TDS has also been conducted. A pristine die has been compared with a similar die that was irradiated with mild nuclear radiation. The channel width measured via T-ray metrology of both dies matches those determined from the optical microscope images. However, T-ray deep-level spectral analysis of both dies reveals that the pristine die's channel structure remains unaffected up to 5.5 THz up to a depth of 3 μm while that of the irradiated die's channel structure's performance is shrunk to 4.2 THz to the same depth of 3 μm. Details of data and analysis have been discussed. The technique may be deployed to other similar systems and devices.

Received: 23 December 2024 | Revised: 27 February 2025 | Accepted: 19 March 2025

Conflicts of Interest

The author declares that he has no conflicts of interest to this work.

Data Availability Statement

Data are available on request from the corresponding author upon reasonable request.

Author Contribution Statement

Anis Rahman: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Project administration.