Influence of InAlN layer Mg doping on the quality of InN/In_0.61Al_0.39N heterostructure deposited by MOCVD

In<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.61</inf>Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.39</inf>N layers were doped by Mg using a variable flow of the Cp<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>Mg precursor at 30 or 80 nmol/min to serve as buffer layers for thin InN layer growth on sapphire substrates by MOCVD. XRD, TEM, SEM, and AFM analyses showed a deterioration of the InAlN structural quality together with phase separation on a nanometer scale with a notable In/Al composition modulation towards the surface of the InAlN layer for the higher Cp<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>Mg flow. The extracted InN electron mobility also decreased from 471 cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>/Vs for the Cp<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>Mg flow of 30 nmol/min to 380 cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>/Vs for the Cp<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>Mg flow of 80 nmol/min.