The paper reports that InP epitaxial layers were grown on iron doped semi-insulating GaAs substrate by low-pressure metalorganic chemical vapor decomposition (LP-MOCVD). Prior to the growth of InP, amorphous InP buffer layer was grown at 400°C, then the substrate zone temperature was raised to the normal InP growth temperature and InP epitaxial layer was grown at 665°C. The obtained InP layers have been characterized by transmission electron microscope, optical microscope, X-ray diffraction, photoluminescence measurement.
This paper describes two kinds of circuit configuration to design interleaver, which are implemented by a single stage M-Z interferometer whose two arms are connected with ring waveguides. When the two configurations circuits are composed of M rings and N rings, respectively, (2M+2N+1)th-order interleaver characteristics can be realized. For two kinds of structure, design examples including third-order interleaver and fifth-order interleaver and seven-order interleaver are demonstrated. By theoretical analysis of the transmission function, The power transmittances spectrums are calculated, the circuit parameters are gained. Compared the power transmittances spectrums among third-order interleaver, fifth-order interleaver and seventh-order interleaver, it is found that with order of interleaver added, flat-top effect is better, the steeper spectral responses of the stopband and passband are achieved, and power transmittances get closer to square wave.
Two-step growth method was used to grow InP epilayers directly on GaAs (001) substrates. By employing double-crystal x-ray diffraction (XRD) to characterize the epilayers and analyzing the value of full width at half maximum (FWHM) of ω scan rocking curve, we found the initial buffer layer act a key role on the quality of epilayers. Depending on optimizing the thickness and growth temperature of the initial buffer layers, we have succeeded in improving the crystallinity of InP epilayers. When the low temperature buffer layer was 10 nm thickness and grown at 450°C, the quality of InP epilayers for 1μm thickness were the best, its FWHM of XRD ω scan rocking curve was only 512 arcsec and 201arcsec for ω-2θ scans, the room temperature photoluminescence spectrum shows the band edge transition of InP, its central wavelength is 921nm and the FWHM is only 38 meV.These results indicate high quality of InP epilayers on GaAs substrates.