BAlN thin layers for deep UV applications

Abstract

International audienceIn this work, wurtzite BAlN layers with boron composition as high as 12% were successfully grown by MOVPE. The growth was performed at 650 °C and then annealed at 1020 °C. Low temperature growth was used in order to alleviate B-rich phase poisoning under high TEB/III ratio. The growth was performed by continuous epitaxy as well as by flow-modulate epitaxy. BAlN single layers with clearly defined X-ray diffraction peaks were achieved on AlN templates which are appropriate substrates for deep UV devices, as well as on GaN templates to facilitate distinguishing of the XRD peak of BAlN from the substrate peak. The layer demonstrated columnar crystalline features and inherited wurtzite structure from substrates.Cross-section STEM image (bright field) of 75 nm thick BAlN layers containing 12% boron taken along the [11−2 0] zone axis. Zone A is lattice-oriented along c-axis and zone B has columnar structure; (b) higher magnification image for the top part of the layer; (c) higher magnification image for the film/substrate interface

100‐nm thick single‐phase wurtzite BAlN films with boron contents over 10%

“…It is known that the composition analysis by XRD can have errors due to lack of reported lattice parameters of BAlN with different compositions and material defects . In this work, the Rutherford backscattering spectrometry (RBS) measurement and simulation were conducted by EAG Laboratories to determine the boron content.…”

“…To further mitigate the parasitic reaction, small V/III ratios of 58 and 39 were used for BAlN‐I and BAlN‐II in the vapor phase, respectively. Previously the suppression of parasitic reaction during the BAlN growth was studied . However, the growth efficiency of BAlN epitaxy has not been reported, making it difficult to evaluate the effect of the implemented methods.…”

“…Phase separation, short diffusion length of boron atoms, and strong parasitic reaction in the gas phase were attributed to the small boron contents. Recently, Li et al reported on the growth of BAlN by a T‐shape horizontal metalorganic chemical vapor deposition (MOCVD) reactor with a much higher boron content of 12% . However, the single‐phase wurtzite structure was only observed in the first 10 nm or thinner region of the BAlN film.…”

MOVPE grown periodic AlN/BAlN heterostructure with high boron content

“…High boron containing layers growth by MOVPE has not been progressed a lot, which might be because the growth is normally performed at 1000 1C or above [2,4,10,11] in order to enhance B atoms diffusion, but at this high temperature the B-rich phase would poison the growth under high TEB/III ratio [12,13]. Low growth temperature can alleviate this problem and high boron incorporation can be achieved [13], but it does not facilitate growth of AlN for heterostructures or AlGaN MQWs. The fabrication of heterostructure is an important issue which needs to be further developed no matter for BAlGaN based MQWs or for DBRs.…”

Effect of Boron Incorporation on Structural and Optical Properties of AlN Layers Grown by Metal‐Organic Vapor Phase Epitaxy

“…Therefore, the microstructures of group‐III nitrides have been intensively studied by transmission electron microscopy (TEM), which enables the direct evaluation of crystalline defects. Recently, the microstructures of the wurtzite BAlN layer with [B] as high as 12% were investigated by Li et al However, the BAlN layers had a columnar‐polycrystalline feature due to heavy B doping. Therefore, to discuss the microstructure of the BAlN layer in detail, further improvement of the crystalline quality of the BAlN layer is required by decreasing [B].…”