Akademik Veri Yönetim Sistemi
ADVANCES IN LASER AND OPTICS RESEARCH, VOL 4, cilt.4, ss.205-221, 2010 (Hakemli Dergi)
Ion beam (IBE), chemically assisted ion beam (CAIBE) and reactive ion (RIE) etching of InP are reported comparatively. Fabrication and characterisation of InP-based semiconductor lasers are also presented here using dry etching methods. While Argon (Ar) alone is used for the IBE process, the CAIBE and RIE are carried out by using Ar/H-2/CH4 and H-2/CH4 chemistries, respectively. The realisation of CAIBE in Ar/H-2 atmosphere is also achieved. In the first part of the work, the evolution of the surface roughness and morphology is presented comparatively for the IBE and CAIBE methods by varying acceleration voltage (V-acc), discharge current (I-dis) and ion incidence angle. It is found that a drastic improvement of the surface roughness is observed for the CAIBE using only Ar/H-2 chemistry. RIE etched structures are also compared with the CAIBE etched ones by using Scanning Electron Microscopy (SEM), highlighting a better surface morphology in the RIE mode. A maximum etch rate of 70 nm/min is observed for 1.75 kV acceleration voltage and 45 mA discharge current at 30 degrees ion incidence angle in the case of CAIBE. The etch rate is recorded to be 45 nm/min for the RIE process. In addition, the anisotropy of the InP samples is also presented for two different masks, Al2O3 and Titanium (Ti) in the case of CAIBE and RIE modes. While the anisotropy in the CAIBE etched samples masked with Ti is 83 degrees, a highly anisotropic sidewall profile of similar to 90 degrees is performed in the RIE process. In the second part, the surfaces etched by the three etching methods are quantified using Atomic Force Microscopy (AFM) technique where an rms roughness of 4.3 +/- 0.7 nm is found in the case of using only Ar/H-2 gasses in the CAIBE mode. Highly smooth (2.1 +/- 0.4 nm rms surface roughness) structures are obtained using RIE. Finally, fabrication and characterization of InP-based semiconductor lasers with 2 mu m-wide waveguides are given of the CAIBE and RIE etching methods comparatively using L-I-V (light-current-voltage) and spectral measurement techniques.