Electrical characteristics of n-GaN Schottky contacts on cleaved surfaces of free-standing substrates: Metal work function dependence of Schottky barrier height

The effect of chemical surface treatment on the uncontrolled surface oxide at a GaN surface and on Fermi level pinning at subsequently formed metal/GaN interfaces was investigated for a GaN epitaxial layer grown on a GaN substrate. The impact of several chemical treatments, including photolithography, on the surface oxide and the resultant surface band bending at the GaN surface was examined by X-ray photoelectron spectroscopy. Surface band bending was reduced by the reduction in the amount of uncontrolled surface oxide. The metal/GaN interfaces formed subsequent to these chemical treatments were investigated by electrical measurement for Schottky barrier diodes. We found that the reduction in the

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“…Fermi level pinning at metal/GaN interfaces for this layer. Indeed, the ϕB-ϕM relation has been newly reported [20][21][22] .…”

Section: Introductionmentioning

confidence: 96%

Effects of surface treatment on Fermi level pinning at metal/GaN interfaces formed on homoepitaxial GaN layers

Isobe

Akazawa

2020

Jpn. J. Appl. Phys.

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“…The barrier height (Ф B ) and ideality factor (n) were obtained from the forward currentvoltage (I-V ) characteristics, and are also given in Table I. The I-V characteristics of each diode were analyzed by the following formulas based on the thermionic emission model: 23,24) = -…”

mentioning

confidence: 99%

Reduction of plasma-induced damage in n-type GaN by multistep-bias etching in inductively coupled plasma reactive ion etching

Yamada

Omori

Sakurai

et al. 2019

Appl. Phys. Express

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Plasma-induced damage was reduced by multistep-bias etching that involved a stepwise decrease of the etching bias power (Pbias) and subsequent annealing. The depth of damage at Pbias = 60 W was determined to be 60 nm from the capacitance–voltage characteristics of Ni/Al2O3/etched-GaN metal-oxide-semiconductor diodes. The damaged layer was removed by subsequent etching at Pbias = 5 W and 2.5 W. The residual and shallow damage induced by the low Pbias was then recovered by subsequent annealing at 400 °C. The multistep-bias etching of inductively coupled plasma reactive ion etching was thus confirmed to be effective for achieving a high etching rate with low damage.

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“…We measured the on‐wafer DC current density versus voltage ( J – V ) characteristics at room temperature using a Keysight B1505A parametric power device analyzer with a Cascade EPS150 probe station. The Schottky barrier height ( ϕ B ) was obtained from the J – V characteristics under a sufficiently large forward bias condition (

V > 3 k T / q

) using the following thermionic emission model

J = A * * T^{2} \exp (- \frac{q ϕ_{normalB}}{k T}) \exp (\frac{q V}{n k T})

where q is the elementary charge, k is the Boltzmann constant, T is the temperature, n is the ideality factor, and

A * *

is the effective Richardson constant (24.0 A cm −2 K −2 for GaN). The measured J – V characteristics were fitted using Equation to obtain the barrier height (

ϕ_{normalB}

) and ideality factor ( n ).…”

Section: Methodsmentioning

confidence: 99%

“…where q is the elementary charge, k is the Boltzmann constant, T is the temperature, n is the ideality factor, and A** is the effective Richardson constant (24.0 A cm À2 K À2 for GaN [9] ). The measured J-V characteristics were fitted using Equation (1) to obtain the barrier height (ϕ B ) and ideality factor (n).…”

Section: Current-voltage Characteristicsmentioning

confidence: 99%

Effective Schottky Barrier Height Model for N‐Polar and Ga‐Polar GaN by Polarization‐Induced Surface Charges with Finite Thickness

Suemitsu

Makabe

2020

Physica Status Solidi (b)

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The nitrogen‐polar GaN material system is a promising candidate for high‐frequency applications, such as those in the millimeter‐wave range. Schottky barrier height is one of fundamental parameters necessary for device applications of N‐polar GaN. Herein, vertical Schottky diodes for both N‐polar and Ga‐polar GaN are prepared, and it is found through experiments that the barrier height of N‐polar GaN is smaller than that of Ga‐polar GaN by 0.21 V. This difference in the barrier height stems from the polarization‐induced surface charge layer of a few angstroms thickness under the surface. Numerical calculation of band profiles suggests that a significant band bending caused by the large amount of polarization charges pushes the conduction band energy downward (upward) in the N‐polar (Ga‐polar) surface depending on the sign of the polarization charges, which results in two different effective Schottky barrier heights. This difference is explained by assuming the polarization‐charge layer thickness of about 5 Å. A simple analytical model to estimate the difference in barrier heights between the two polarities is also proposed.

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Electrical characteristics of n-GaN Schottky contacts on cleaved surfaces of free-standing substrates: Metal work function dependence of Schottky barrier height

Cited by 22 publications

References 30 publications

Effects of surface treatment on Fermi level pinning at metal/GaN interfaces formed on homoepitaxial GaN layers

Effects of surface treatment on Fermi level pinning at metal/GaN interfaces formed on homoepitaxial GaN layers

Reduction of plasma-induced damage in n-type GaN by multistep-bias etching in inductively coupled plasma reactive ion etching

Effective Schottky Barrier Height Model for N‐Polar and Ga‐Polar GaN by Polarization‐Induced Surface Charges with Finite Thickness

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