Hydrogen implantation‐induced large area exfoliation in AlN epitaxial layers

Abstract

Hydrogen ion implantation in aluminium nitride (AlN) epitaxial layers grown on 2‐inch c‐plane (0001) sapphire substrates was performed with different fluences in the range of 1 × 1017–2 × 1017/cm2 at various implantation temperatures between liquid nitrogen (LN2) to 300 °C. The post‐implantation thermal annealing behaviour of these samples was studied by using optical microscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM). Our investigations showed that AlN samples that were implanted at LN2 and room temperature (RT) exhibited mostly surface blistering after post‐implantation annealing. On the other hand, the AlN samples that were implanted at 100 and 300 °C showed large area exfoliation of the implanted surface after post‐implantation annealing. The implantation‐induced damage in AlN was analysed by cross‐sectional TEM, which revealed a damage band inside the AlN layer in all the cases that was decorated with hydrogen‐filled nanovoids. These nanovoids showed a greater tendency of agglomerating together to form nanocracks in the as‐implanted state for 100 and 300 °C implanted samples leading eventually to the large area exfoliation after high temperature annealing.

Ion Implantation-Induced Layer Splitting of Semiconductors

“…However, there is no difference between the H-implantation parameters that lead to blistering/exfoliation or layer splitting/layer transfer using direct wafer bonding. In some cases large area exfoliation, where the implanted surface is completely removed over a large regions, also occurs (Dadwal et al, 2010). The detailed understanding of the hydrogen implantation-induced surface blistering mechanisms is very essential from the prospect of successful application for ion-cut process.…”

“…The nitride technology has also attracted great attention towards AlN next to GaN due to its higher direct bandgap and thermal conductivity, and along with some other special physical properties (Dadwal et al, 2010). Hence, it makes AlN as a perfect material for the fabrication of high power lasers and highly efficient UV optoelectronic devices.…”

“…In addition, its radiation hardness aspect makes it suitable material for space and military applications. However, the AlN technology is still in their infancy stages and it needs a greater look-up to study this material not only in the technological but material point of view also (Dadwal et al, 2010). But the fs-AlN wafers are very expensive and are mostly available upto two inch of diameter.…”

“…But the fs-AlN wafers are very expensive and are mostly available upto two inch of diameter. Hence working on these lines, the recent studies are concentrated more towards the material aspects of AlN epitaxial layers and the possibilities of combining it with ion-cut process (Dadwal et al, 2010). Once the ion-cut process gets its maturity in AlN, one can think about the reduction of cost of this AlN technology.…”

“…Even the high quality epitaxial layers of AlN in combination with ion-cut process have a potential for the fabrication of low cost nitride devices. That is why, first part of the ion-cut process which is ion implantationinduced damage study is mostly considered in the recent studies (Dadwal et al, 2010;Singh et al, 2010). It mostly includes the influence of H-implantation and post-implantation annealing parameters on the induced damage.…”