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Title: Sulfuric acid and hydrogen peroxide surface passivation effects on AlGaN/GaN high electron mobility transistors

In this work, we have compared SiN{sub x} passivation, hydrogen peroxide, and sulfuric acid treatment on AlGaN/GaN HEMTs surface after full device fabrication on Si substrate. Both the chemical treatments resulted in the suppression of device pinch-off gate leakage current below 1 μA/mm, which is much lower than that for SiN{sub x} passivation. The greatest suppression over the range of devices is observed with the sulfuric acid treatment. The device on/off current ratio is improved (from 10{sup 4}–10{sup 5} to 10{sup 7}) and a reduction in the device sub-threshold (S.S.) slope (from ∼215 to 90 mV/decade) is achieved. The sulfuric acid is believed to work by oxidizing the surface which has a strong passivating effect on the gate leakage current. The interface trap charge density (D{sub it}) is reduced (from 4.86 to 0.90 × 10{sup 12 }cm{sup −2} eV{sup −1}), calculated from the change in the device S.S. The gate surface leakage current mechanism is explained by combined Mott hopping conduction and Poole Frenkel models for both untreated and sulfuric acid treated devices. Combining the sulfuric acid treatment underneath the gate with the SiN{sub x} passivation after full device fabrication results in the reduction of D{sub it} and improves the surface related current collapse.
Authors:
; ; ; ;  [1] ; ; ;  [2]
  1. Department of Electronic and Electrical Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)
  2. Department of Materials Science and Metallurgy, The University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)
Publication Date:
OSTI Identifier:
22399180
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 24; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALUMINIUM COMPOUNDS; CHARGE DENSITY; COMPARATIVE EVALUATIONS; ELECTRON MOBILITY; EV RANGE; FABRICATION; GALLIUM NITRIDES; HYDROGEN PEROXIDE; INTERFACES; LEAKAGE CURRENT; PASSIVATION; SILICON; SUBSTRATES; SULFURIC ACID; SURFACES; TRANSISTORS; TRAPS