Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

Abstract

The effects of surface pretreatment, dielectric growth, and post deposition annealing on interface electronic structure and polarization charge compensation of Ga-and N-face bulk GaN were investigated. The cleaning process consisted of an ex-situ wet chemical NH 4 OH treatment and an in-situ elevated temperature NH 3 plasma process to remove carbon contamination, reduce oxygen coverage, and potentially passivate N-vacancy related defects. After the cleaning process, carbon contamination decreased below the x-ray photoemission spectroscopy detection limit, and the oxygen coverage stabilized at $1 monolayer on both Ga-and N-face GaN. In addition, Ga-and N-face GaN had an upward band bending of 0.8 6 0.1 eV and 0.6 6 0.1 eV, respectively, which suggested the net charge of the surface states and polarization bound charge was similar on Ga-and N-face GaN. Furthermore, three dielectrics (HfO 2 , Al 2 O 3 , and SiO 2 ) were prepared by plasma-enhanced atomic layer deposition on Ga-or N-face GaN and annealed in N 2 ambient to investigate the effect of the polarization charge on the interface electronic structure and band offsets. The respective valence band offsets of HfO 2 , Al 2 O 3 , and SiO 2 with respect to Ga-and N-face GaN were 1.4 6 0.1, 2.0 6 0.1, and 3.2 6 0.1 eV, regardless of dielectric thickness. The corresponding conduction band offsets were 1.0 6 0.1, 1.3 6 0.1, and 2.3 6 0.1 eV, respectively. Experimental band offset results were consistent with theoretical calculations based on the charge neutrality level model. The trend of band offsets for dielectric/GaN interfaces was related to the band gap and/or the electronic part of the dielectric constant. The effect of polarization charge on band offset was apparently screened by the dielectric-GaN interface states. V C 2014 AIP Publishing LLC.

Interface formation of Al2O3 on n‐GaN(0001): Photoelectron spectroscopy studies

“…Adequate energy band diagram of the interface is shown in Figure 5. Calculated here, VBO value differs from those reported by other authors 12,18,30,49 ; the results obtained by them vary from −0.7 to −2.0 eV. Since these discrepancies of the VBO values also apply to studies where the same deposition technique was used, 12,18,49,71 properties of the oxide film, which result from the deposition technique used.…”

“…Calculated here, VBO value differs from those reported by other authors 12,18,30,49 ; the results obtained by them vary from −0.7 to −2.0 eV. Since these discrepancies of the VBO values also apply to studies where the same deposition technique was used, 12,18,49,71 properties of the oxide film, which result from the deposition technique used. It is known that the ALD gives less dense film 17 and that the VBO/CBO values depend on the growth method, 75 also the bandgap of the oxide adlayer depends on the film density 17 and varies from 6.2 to 7.0 eV for an amorphous film.…”

“…It is known that the ALD gives less dense film 17 and that the VBO/CBO values depend on the growth method, 75 also the bandgap of the oxide adlayer depends on the film density 17 and varies from 6.2 to 7.0 eV for an amorphous film. 10,12,[16][17][18]30,76 4 | CONCLUSIONS…”

Quantum‐Tunneling Metal‐Insulator‐Metal Diodes Made by Rapid Atmospheric Pressure Chemical Vapor Deposition

“…The barrier height (φ) is the difference between the work function of the metal (ψ) and the electron affinity of the insulator (χ). The electron affinity of Al 2 O 3 fabricated by PEALD has been reported as 1.90 ± 0.2 eV and the work function of Pt and Al are ≈5.69 and 4.28 eV, respectively. Therefore, the left barrier height at the Pt–Al 2 O 3 interface is expected to be approximately φ L = 3.79 eV, and the right barrier height at the Al–Al 2 O 3 interface is expected to be approximately φ R = 2.38 eV.…”

Precise determination of surface band bending in Ga-polar n-GaN films by angular dependent X-Ray photoemission spectroscopy

“…Surface band bending plays an important role in semiconductor devices by modifying the basic electronic properties and efficiency of them 6 . The effective electron surface band bending results from the complex superposition of contributions from localized surface state charges and polarization charges in wurtzite GaN crystal, and directly affects the device performance 7 . It has been reported that heavily Si doped GaN ohmic layers, in lateral contact to two-dimensional electron gas in the GaN channel, could dramatically improve the DC and RF characteristics in GaN-high electron mobility transistors (GaN-HEMT) 8 .…”