Fabrication of vertical Schottky barrier diodes on n-type freestanding AlN substrates grown by hydride vapor phase epitaxy

Abstract

Thick Si-doped AlN layers were homoepitaxially grown by hydride vapor phase epitaxy on AlN(0001) seed substrates. Following the removal of the seed substrate, an n-type AlN substrate with a carrier concentration of 2.4 × 1014 cm−3 was obtained. Vertical Schottky barrier diodes were fabricated by depositing Ni/Au Schottky contacts on the N-polar surface of the substrate. High rectification with a turn-on voltage of approximately 2.2 V was observed. The ideality factor of the diode at room temperature was estimated to be ∼8. The reverse breakdown voltage, defined as the leakage current level of 10−3 A/cm2, ranged from 550 to 770 V.

Barrier Inhomogeneity of Schottky Diode on Nonpolar AlN Grown by Physical Vapor Transport

“…At high reverse biases, the value of the capacitance was affected by the leakage current, which is relatively high for the bare SBD. The electron density n e was estimated to be 2 × 10 14 cm -3 from the simplified charge-neutrality equation, n e 2 = (N D N C /2)exp(-E D /kT), where N C is the effective density of states in the conduction band [18]. Then the energy difference E F between the Fermi level and the conduction band minimum was found to be 273 meV from the equation n e = N C exp(-E F /kT).…”

High Lateral Breakdown Voltage in Thin Channel AlGaN/GaN High Electron Mobility Transistors on AlN/Sapphire Templates

“…An AlN-based material system has a unique advantage due to its prominent spontaneous and piezoelectric polarization effects, but also its flexibility in inserting appropriate heterojunctions, thus dramatically broadening the device’s design space. Furthermore, AlN material represents the ideal back barrier for high voltage HEMT applications due to its large electrical breakdown field combined with a high thermal conductivity [14,15,16,17]. In turn, the AlN buffer can potentially not only increase the electron confinement in a transistor channel, but can also help to boost the breakdown voltage (BV), owing to its wider bandgap, while benefiting from an enhanced thermal dissipation as compared to GaN-based devices [18,19,20].…”

AlN metal–semiconductor field-effect transistors using Si-ion implantation

“…11,12) However, Schottky-barrier diodes and deep-ultraviolet light-emitting diodes are among the few AlN-channel devices reported in the literature so far. 13,14) Due to the lack of suitable higher band-gap materials for hetero-structures, polarization induced doping cannot be utilized to generate electron conduction in AlN. Thus, the formation of an AlN channel requires impurity-doped AlN layers.…”