Surface treatments of CdGeAs2 single crystals

• Published in: Rare metals 2019-07, Vol.38 (7), p.683-688
• Main Authors: Huang, Wei, Zhao, Bei-Jun, Zhu, Shi-Fu, He, Zhi-Yu, Chen, Bao-Jun, Zhen, Zhen, Pu, Yun-Xiao
• Format: Article
• Language: English
• Subjects: Atomic force microscopy; Biomaterials; Chemical polishing; Chemical-mechanical polishing; Chemistry and Materials Science; Energy; Germanium; Germanium oxides; Materials Engineering; Materials Science; Metallic Materials; Microscopes; Microscopy; Nanoscale Science and Technology; Optical microscopy; Optical Parametric Oscillators; Organic chemistry; Parametric amplifiers; Photoelectrons; Physical Chemistry; Roughness; Scanning electron microscopy; Second harmonic generation; Single crystals; Surface properties; X ray photoelectron spectroscopy
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-016-0818-0

The performances of second harmonic generation (SHG) and optical parametric oscillator (OPO) in CdGeAs 2 crystal are strongly influenced by surface quality. In this paper, the surfaces of samples were treated by mechanical polishing (MP), chemical polishing (CP), chemical–mechanical polishing (CMP) and CP following CMP closely (CMP + CP). Then, the surface state was characterized by optical microscopy (OM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). AFM measurements show that an ultra-smooth surface is achieved after CMP + CP treatment and the roughness value is 0.98 nm. Meanwhile, the roughness of the surfaces treated by MP, CP and CMP are 4.53, 2.83 and 1.38 nm, respectively. By XRD rocking curves, the diffraction peak which belongs to the wafer treated by CMP + CP is the highest in intensity and best symmetrical in shape. XPS analysis indicates that Ge 4+ proportions of GeO 2 in total Ge content of CdGeAs 2 wafers’ surface after MP, CP, CMP and CMP + CP treatment are 27.6%, 42.8%, 6.1% and 30.3%, respectively.