Competition between diamond nucleation and growth under bias voltage by microwave plasma chemical vapor deposition

Diamond nucleation on iridium (001) substrates was investigated under different bias conditions. High-density epitaxial nucleation can be obtained in a narrow bias window. This paper reports both the typical nucleation and growth behaviors of Ir substrates. The bias current change laws with the bias duration time were directly recorded; further, the surface modification of Ir substrates and nucleation behaviors at the interface were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In high-density epitaxial nucleation, the bias current decreases as the duration time increases when the iridium surface is dramatically modified with the furrows and arrows preferentially aligned along the [110] direction; however, no diamond grains can be observed from the TEM, except for the carbon layer at the interface. In bias-enhanced growth, the bias current initially decreased, then increased. The grains can be detected by SEM after the biasing stage. A competition mechanism between diamond nucleation and growth under a bias voltage is proposed for this phenomenon, in which the surface nucleation and bulk nucleation coexist and compete.

Automated summary

Diamond nucleation on iridium (001) substrates was investigated under different bias conditions, revealing that high-density epitaxial nucleation can be achieved in a narrow bias window. In bias-enhanced growth, the bias current initially decreases, then increases, indicating a competition mechanism between diamond nucleation and growth.