A Novel Method For The Diffusion Of Boron In 60-80 Micron Size Natural Diamond Type II/A Powder

Abstract

ABSTRACTThe purpose of this paper is to report the experimental results of boron doping on 60-80 micron size diamond particles using Field Enhanced Diffusion with Optical activation (FEDOA) [1-5]. Diamond is a wide band gap material with unique combinations of optical, thermal, mechanical and electronic properties that can be useful for a number of applications including optoelectronic applications and micro sensor technology. The incorporation of boron into diamond has been proven to change its electrical properties and convert the diamond from insulator to a p-type semiconductor [3]. A promising technique for incorporation of impurities into diamond is FEDOA. FEDOA drives impurities into single crystalline diamond material and we have used this method in this study [5-7]. FEDOA uses a combination of thermal diffusion with bias plus thermal ionization and optical ionization I simultaneously. A modified version of FEDOA was implemented for the diffusion of boron in natural diamond type II/a powder of size 60-80 microns (Figure 1). The diamond powder was obtained from Microdiamant and has 99.9% purity. The boron powder used in the experiment was amorphous, 325 mesh 90 %(Assay), Mg (5%) nominal obtained from AESAR. A ratio of 3:1 Boron-Diamond mixture was used for the doping process. A heating element and a diamond-boron powder mixture holder were designed and incorporated in the FEDOA system. Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS) were used to study the diamond-doped morphology and identify impurities. Boron and hydrogen concentration results in the doped samples were studied using Prompt Gamma Neutron Activation Analysis (PGNAA) at the University of Missouri Research Reactor (MURR). Raman analysis of the treated samples was done as part of this work. The experimental results and analysis show that the samples were doped with boron. It was also found that samples with high boron concentration exhibited a high electrical conductivity. This work presents additional evidence that boron can be diffused into natural diamond powders. It also demonstrates that the FEDOA diffusion process is not only a powerful technique for the diffusion of impurities into wide band-gap materials in the form of single crystal plates, polycrystalline plate but also in a powder form with the modified FEDOA process.