Electrical and chemical characterization of the Schottky barrier formed between clean n-GaN(0001) surfaces and Pt, Au, and Ag

Abstract

Platinum, gold, and silver formed abrupt, unreacted, smooth, and epitaxial metal–semiconductor interfaces when deposited from the vapor onto clean, n-type GaN(0001) films. The Schottky barrier heights, determined from data acquired using x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, capacitance–voltage, and current–voltage measurements agreed to within the experimental error for each contact metal and had the values of 1.2±0.1, 0.9±0.1, and 0.6±0.1 eV for Pt, Au, and Ag, respectively. The band bending and the electron affinity at the clean n-GaN surface were 0.3±0.1 and 3.1±0.1 eV, respectively. The barrier height is proportional to the metal work function, indicating that the Fermi level is not pinned at the GaN surface. However, discrepancies to the Schottky–Mott model were found as evidenced by a proportionality factor of 0.44 between the work function of the metal and the resulting Schottky barrier height. The sum of these discrepancies constitute the interface dipole contributions to the Schottky barrier height which were measured to be ∼1.4, 1.3, and 0.7 eV for Pt, Au, and Ag, respectively.

Transparent Conducting Polymer/Nitride Semiconductor Heterojunction Solar Cells

“…The determined diode characteristics of the TCP/epi.-GaN heterojunction determined from the J-V characteristics and capacitance measurements are summarized in Table 2. The observed barrier height was comparable to that obtained by conventional metal Schottky contacts (Tracy et al, 2003). In the case of the conventional metal Schottky contacts, elaborate surface cleaning processes and moderate metal deposition in ultra-high-vacuum conditions are required to attain good Schottky contact with a  B of more than 1 eV.…”

Study of schottky barrier heights of indium-tin-oxide on p-GaN using x-ray photoelectron spectroscopy and current-voltage measurements

“…9. 23,24 This equation was previously employed by Tracy et al 25 for the calculation of the barrier heights (qφ n ) of metals on n-GaN. qφ n ϭE G -E i V ϩ(E i core -E m core )ϭE G -(E m core -E VC ) (9) where E G is the bandgap of the semiconductor, E mcore is the binding energy of the semiconductor corelevel peak following metal deposition, E i core is the initial binding energy of the core-level peak, E i V is the initial binding energy of the E V of the semiconductor, and E VC is equal to (E i core -E i V ).…”

Improved Light Output of GaN-Based Light-Emitting Diodes by Using AgNi Reflective Contacts

“…10 The Ga 2p peak shift implies a change of the band bending since the N 1s core-level spectra show a similar shift behavior. 19 It is noteworthy that the shift increases with increasing Ni content. This could be attributed to the increased contact area between the metal reflectors and p-GaN due to the suppression of the agglomeration of the AgNi reflectors, as demonstrated by the SEM results (Fig.…”