Investigation of annealed, thin(∼2.6 nm)-Al2O3/AlGaN/GaN metal-insulator-semiconductor heterostructures on Si(111) via capacitance-voltage and current-voltage studies

H. P. Lee, C. Bayram

Research output: Contribution to journalArticlepeer-review


Annealed, thin(∼2.6 nm)-Al2O3/AlGaN/GaN metal-insulator-semiconductor (MIS) heterostructures on Si(111) are fabricated and studied via capacitance-voltage (C-V) measurements to quantify densities of fast and slow interface trap states and via current-voltage (I-V) measurements to investigate dominant gate current leakage mechanisms. Dual-sweep C-V measurements reveal small voltage hysteresis (∼1 mV) around threshold voltage, indicating a low density of slow interface trap states of ∼109 cm-2. Frequency-dependent conductance measurements show fast interface trap state density ranging from 8 × 1012 to 5 × 1011 eV-1 cm-2 at energies from 0.275 to 0.408 eV below the GaN conduction band edge. Temperature-dependent I-V characterizations reveal that trap-assistant tunneling (TAT) dominates the reverse-bias carrier transport while the electric field across the Al2O3 ranges from 3.69 to 4.34 MV cm-1, and the dominant Al2O3 trap state energy responsible for such carrier transport is identified as 2.13 ± 0.02 eV below the Al2O3 conduction band edge. X-ray photoelectron spectroscopy measurements on Al2O3 before and after annealing suggest an annealing-enabled reaction between Al-O bonds and inherent H atoms. Overall, we report that annealed, thin-Al2O3 dielectric is an effective (Al)GaN surface passivation alternative when minimizing passivation-associated parasitic capacitance is required, yet non-ideal for significantly suppressing gate leakage current in MIS structures due to the governing TAT carrier transport mechanism.

Original languageEnglish (US)
Article number105904
JournalMaterials Research Express
Issue number10
StatePublished - Aug 9 2019


  • AlGaN
  • GaN
  • atomic layer deposition AlO
  • high electron mobility transistor
  • interface trap states
  • metal-insulator-semiconductor hetero-structure
  • surface passivation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Metals and Alloys


Dive into the research topics of 'Investigation of annealed, thin(∼2.6 nm)-Al<sub>2</sub>O<sub>3</sub>/AlGaN/GaN metal-insulator-semiconductor heterostructures on Si(111) via capacitance-voltage and current-voltage studies'. Together they form a unique fingerprint.

Cite this