Surface characterization and luminescence properties of AlN doped with RE elements (Sm, Ho, Gd, Tm)

Abstract

Rare‐ earth (RE)‐doped III‐nitride broad band‐gap semiconductors have attracted enormous interest as a foundation for optoelectronics devices, which combine the unique luminescence feature of Rare‐earth ions with the electronic properties of the semiconductors. Recent progress toward nitride‐based light emitting diode and light emitting due to electric current devices have been made using crystalline and amorphous AlN and GaN doped with a different lanthanide elements. The Rare‐earth ions’ electronic structures are differ from the other elements and are unique due to an incompletely filled 4Fn shell. The 4F‐orbital electrons lay inside the ion and are protected from the surroundings by the filled 5S2 and 5P6 electron orbitals. When these rare‐earths doped are excited by any external means, intense sharp‐line emission is observed due to intra‐4Fn shells transitions of the rare‐earth ion core. In the present work, sputtered deposited thin films of AlN doped with rare‐earth elements (Sm, Ho, Gd, Tm) are investigated for their structures, luminescence and spectroscopic properties. Thin films were deposited at various temperatures. X‐ray diffraction (XRD) analysis was performed for structural analysis and crystallite size calculation in crystalline films. Scanning electron microscopy was also used to confirm the information obtained from XRD. Luminescence and spectroscopic analysis were performed using photoluminescence tool and Fourier transform infra‐red. The effect of the temperature on the surface morphology and luminescence properties was also studied. Energy dispersive x‐ray analysis was performed on the films to find the constituents and impurities in the samples. Atomic force microscopy was also used for determination of surface roughening, and thermal gravimetric analysis was used to investigate loss of mass of the samples over a range of temperature. This work provides investigations of these materials for their use in photonic and microelectronic devices.