Improvement of Crystal Quality of a Homoepitaxially Grown Diamond Layer Using Plasma Etching Treatment for a Diamond Substrate

To realize a practical application of synthetic diamond radiation detectors, an effort to synthesize high-quality diamond single crystals was conducted using microwave plasma assisted chemical vapor deposition (CVD). This study evaluated the influence of etching treatment––a reactive ion-etching technique used for diamond substrates––on the crystal quality of a homoepitaxially grown diamond layer. A type Ib diamond single crystal grown using a high-temperature and high-pressure method was used as the substrate. Homoepitaxial diamond layers with ca. 10 m thickness were grown on diamond substrates with different etching depths. Then observations were conducted using a differential interference microscopy and cathode luminescence spectroscopy. Judging from the intensity of free exciton recombination luminescence and other observations, the crystal quality was markedly improved by the etching treatment on the diamond substrates. Furthermore, a macroscopic complex of abnormal growth resulting from a mechanical polished flaw was almost removed by the etching treatment with etching depth of 2.6 m.