Effect of Anodic Oxidation on the Characteristics of Lattice-Matched AlInN/GaN Heterostructures

Abstract

The effect of anodic oxidation on the electronic characteristics of lattice-matched AlInN/GaN heterostructures was investigated using field-effect transistor (FET) structures with the gate areas in direct contact with the electrolytes. The gate surface of the FETs was subjected to anodic oxidation in 0.1 M KOH. The oxidized heterostructures were analyzed by electrochemical impedance spectroscopy and by modeling the characteristics of the electrolyte-gate FETs and the energy-band diagram of the heterostructures. This analysis suggested that the anodic treatment induced a bulk oxidation of the AlInN barrier. The Fermi level at the oxidized AlInN surface was shifted deep into the bandgap. The oxidation led to a reduction of the carrier mobility and to partial depletion of the channel.

Surface potential analysis of AlN/GaN heterostructures by electrochemical capacitance-voltage measurements

“…The potential window of water dissociation, which is limited by hydrogen evolution and negative and oxygen evolution at positive potentials, is slightly below 3 V, similar to that of other III-nitrides. 10,13 Within this window, the current is determined by charging and discharging of the interface capacitance, and electrochemical measurements of the heterostructure are possible without strong anodic oxidation or cathodic etching. The hysteresislike characteristics of hydrogen and oxygen evolution currents might be explained by slow adsorption and desorption of intermediate products formed during the reactions.…”

“…The double layer capacitance was taken to be $10 lF/cm 2 and potential-independent, similar to previous studies. 10,12 The corresponding applied flatband potential V FB,appl ¼ À1.6 V partially drops across the double layer capacitance (DV DL ) and partially across the depletion layer capacitance (DV SC ) in the semiconductor in series. The potential drop across the GaN can be calculated by…”

“…5 In the case of lattice-matched InAlN/GaN heterostructures grown by metal-organic chemical vapor deposition (MOCVD), a constant and relatively low surface potential of $0.6-0.8 eV has been extracted. 9,10 For the case of AlN/GaN heterostructures, no detailed data are available so far up to our knowledge. Here it is important to note that AlN barrier layers of high quality can only be grown up to a thickness of 4-6 nm due to the large lattice constant mismatch to GaN.…”

InAlN - A new barrier material for GaN-based HEMTs

“…In the corresponding experiment [9] the FET structure had been operated in the liquid (in the ISFET mode), where the barrier layer had been in direct contact with the electrolyte in the gate area. Shown is the change of the sheet charge density with oxidation treatment, whereby the level had been related to the heterostructure configuration and here especially the barrier layer thickness of 10 nm and the surface potential of the electrochemical gate electrode.…”

Magnetron Sputter Epitaxy and Characterization of Wurtzite AlInN on Si(111) Substrates

“…Moreover, the Al 0.83 In 0.17 N alloy can be used as a cladding layer on a GaN-based laser diode without causing strain, and this usually leads to a reduction in defects because of their well-matched lattice constants. [1][2][3][4][5][6][7][8][9][10][11][12] However, only a few papers in the literature have reported the growth of AlInN alloys. This is probably because of the fact that AlN and InN have different thermal stabilities and covalent bonds, which usually leads to compositional inhomogeneity and phase separation while forming alloys.…”