Anomalous Ion Channeling inAlInN/GaNBilayers: Determination of the Strain State

Abstract

Monte Carlo simulations of anomalous ion channeling in near-lattice-matched AlInN/GaN bilayers allow an accurate determination of the strain state of AlInN by Rutherford backscattering or channeling. Although these strain estimates agree well with x-ray diffraction (XRD) results, XRD composition estimates are shown to have limited accuracy, due to a possible deviation from Vegard's law, which we quantify for this alloy. As the InN fraction increases from 13% to 19%, the strain in AlInN films changes from tensile to compressive with lattice matching predicted to occur at [InN] = 17.1%.

Composition and luminescence of AlInGaN layers grown by plasma-assisted molecular beam epitaxy

“…In our experience WDX provides composition data of similar accuracy to that from Rutherford backscattering spectrometry ͑RBS͒. 10,11 Advantages of WDX over RBS include the higher lateral spatial resolution ͑down to 100 nm͒ and the possibility of simultaneous CL spectroscopy, while RBS has much better depth resolution. These methods have some advantages compared to measurement of AlInGaN composition using standard x-ray diffraction, which can be complicated by the lack of a unique solution for the quaternary system.…”

( In , Ga ) N ∕ Ga N microcavities with double dielectric mirrors fabricated by selective removal of an (Al,In)N sacrificial layer

“…This ultimately acts as a sacrificial layer in a selective wet etching step, 11 but also allows endpoint detection during plasma etch steps which precede this. The sacrificial Al 0.83 In 0.17 N is lattice matched to GaN, 3,12 and the high quality of GaN grown above such a layer has recently been confirmed by spectroscopic and structural characterization. 13 The refractive index contrast between Al 0.83 In 0.17 N and GaN is also valuable in facilitating in situ reflectometry during epitaxy on FS-GaN.…”

Breakdown of anomalous channeling with ion energy for accurate strain determination in GaN-based heterostructures

“…The potential of RBS/C has been proved on several semiconductor heterostructures ͑HSs͒, where elastic strain is a main issue affecting band gap and carrier density. 3 However, this kind of RBS/C studies has shown anomalous behaviors in the angular scans ͑asymmetries or double dips͒, [4][5][6] which decrease the accuracy in the strain determination. The origin of these anomalous channeling processes has been clearly linked to the presence of steering effects ͑deviation of the projectile due to electrostatic interactions with the target atoms͒ at the interface of the junction.…”

“…The origin of these anomalous channeling processes has been clearly linked to the presence of steering effects ͑deviation of the projectile due to electrostatic interactions with the target atoms͒ at the interface of the junction. 5 The thickness of the layer and the strain state strongly influence this behavior since the steering operates when ⌬ is smaller or comparable to the critical angle for channeling ͑ 1 ͒. 7 In some cases, this error can be corrected by additional Monte Carlo ͑MC͒ simulations, 5,7 but in others this approach is not sufficient.…”

“…5 The thickness of the layer and the strain state strongly influence this behavior since the steering operates when ⌬ is smaller or comparable to the critical angle for channeling ͑ 1 ͒. 7 In some cases, this error can be corrected by additional Monte Carlo ͑MC͒ simulations, 5,7 but in others this approach is not sufficient. However, 1 is given by Lindhard's relation 2 1 = ͑2Z 1 Z 2 e 2 / Ed͒ 1/2 and, therefore, the beam energy can be tailored to reduce the steering at the interface, which opens an alternative way for the accurate determination of the strain in crystalline HSs.…”