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Depth-resolved analysis of spontaneous phase separation in the growth of lattice-matched AlInN

A. Redondo-Cubero 1,2,* , K. Lorenz 3 , R. Gago 4 , N. Franco 3 , M.-A. di Forte Poisson 5 , E. Alves 3 and E. Muñoz 1
1 ISOM and Dpt. de Ingeniería Electrónica, ETSI Telecomunicación, Universidad Politécnica de Madrid,
E-28040 Madrid, Spain.
2 Centro de Micro-Análisis de Materiales, Universidad Autónoma de Madrid,
E-28049 Madrid, Spain.
3 Instituto Tecnológico e Nuclear,
Estrada nacional 10, 2686-953 Sacavém, Portugal.
4 Instituto de Ciencia de Materiales de Madrid (CSIC),
E-28049 Madrid, Spain.
5 Thales Research & Technology/TIGER,
91461 Marcoussis Cedex, France.

ABSTRACT: We report the detection of phase separation of an Al 1-x In x N/GaN heterojunction grown close to lattice matched conditions (x∼0.18) by means of Rutherford backscattering spectrometry in channeling geometry and high resolution x-ray diffraction. An initial pseudomorphic growth of the film was found, with good single crystalline quality, the nominal composition and very low strain state. After ~50 nm, a critical thickness is reached at which the InN molar fraction of the films drops to ~15 % and at the same time the single crystalline quality of the films degrade drastically. This spontaneous effect cannot be ascribed to strain relaxation mechanisms since both techniques show a good single crystalline growth of the ternary under lattice matched conditions.

Keywords: RBS, channeling, AlInN, strain, XRD

[* Corresponding author:]

andres.redondo@uam.es 1. INTRODUCTION