Structural transformation of implanted diamond layers during high temperature annealing

TL;DR

This study investigates how high-temperature annealing transforms implanted diamond layers, revealing partial to complete graphitization and nano-crystal formation, which impacts the optical interface quality in device fabrication.

Contribution

It provides detailed insights into the structural changes and graphitization process of implanted diamond layers during annealing, using TEM analysis.

Findings

Partial graphitization at 550°C with nano-crystalline graphite formation

Complete graphitization at 1400°C with small graphite nano-crystals

Nano-crystals predominantly oriented with c-planes normal to surface

Abstract

In the recent years graphitization of ion-beam induced amorphous layers became the basic tool for device fabrication in diamond. The etchable graphitic layers can be removed to form free-standing membranes into which the desired structures can be sculpted using FIB milling. The optical properties of the devices fabricated using this method are assumed on the model of sharp diamond-air interface. The real quality of this interface could depend on degree of graphitization of the amorphous damage layers after annealing. In the present work the graphitization process was studied using conventional and analytical TEM. It was found that annealing at 550 {\deg}C results in a partial graphitization of the implanted volume with formation of the nano-crystalline graphitic phase sandwiched between layers of tetrahedral amorphous carbon. Annealing at 1400 {\deg}C resulted in complete graphitization of the amorphous layers. The average size of graphite nano-crystals did not exceed 5 nm with predominant orientation of c-planes normal to the sample surface.