Development of AlNB alloy in (Al/AlN/B) stacking sequence using RF reactive sputtering towards thermal management application

Abstract

In this paper, we present the development and performance analysis of AlNB alloy for thermal management applications. The AlNB alloy at nanoscale film thickness is grown in stack configuration of (Al-AlN-B) on modified aluminium (Al) substrates (5052) using reactive sputtering at room temperature and annealed at 400 °C under nitrogen ambient. Cubic aluminium nitride (c-AlN) structures with (200) and (220) orientations are confirmed by the X-ray diffractometer (XRD) analysis. Furthermore, the presence of AlN and boron nitride (BN) is established from Fourier-transform infrared spectroscopy (FTIR) spectra. The measured film thickness of the AlNB alloy films is in the range from ~ 157.4 to 378.8 nm, while the particle sizes are in the range between ∼80 and 300 nm. The measured roughness of the films is in the range ~ 54 and 82 nm for the three samples, by the processing of Atomic Force Microscopy (AFM) images using Nanoscope software. However, from the cumulative structure function analysis, the total thermal resistance of the light-emitting diode (LED) (R_thj-a) is reduced by about ~ 4 to ~ 23%, with samples 1 (AlN/B), 2 (AlN/B/AlN/B) and 3 (AlN/B/AlN/B/AlN) as compared to that of bare Al substrate. Previous literature on similar material indicates higher thermal resistance of about 43–53 (K/W); however, in our work, we were able to achieve low R_th of 8.5 (K/W) as reported in this paper. Furthermore, considering the structural properties, surface, and good thermal performance coupled with lower bond line thickness (BLT) in ~ 150 nm range exhibited by the grown alloy, the developed material is therefore recommended for effective thermal management application of LEDs and other solid-state devices at low and high operational current densities.