We have analyzed low temperature (12 K) photoluminescence (PL) characteristics of carbon(C) doped GaAs epilayers. No traces of donor levels were observed in the PL spectra. This suggest that well-behaved carbon is incorporated as an acceptor into the GaAs lattice. The measured peak energy of the PL intensity distribution shifts to lower energy and the full width at half maximum (FWHM) increases with increasing hole concentration. We have obtained empirical relations for FWHM of PL intensity distribution in two distinct hole concentration regions. These relations are considered to provide a useful tool to determine free hole concentration in C doped GaAs by low temperature PL measurements. As the hole concentration is increased above 2×1019 cm−3, a shoulder separated from the PL peak was observed in the PL spectra at Eg+EF, where  Eg is the band gap and EF is the Fermi energy. The shoulder became very prominent at 9.2×1019 cm−3.

X-ray rocking curve measurements showed a significant crystallographic tilt in relaxed InGaAs layer grown on (001) GaAs. Transmission electron microscopy revealed that the origin of tilt is 60° dislocations generated having Burgers vectors of a same vertical edge component. Calculations using anisotropic elasticity show that this configuration of 60° dislocation array is energetically favorable when the tilt of epilayer is present as to remove the long range stress field induced by the vertical edge components at the interface.

We have observed the remarkable increase of GaAs lateral growth rate in the presence of CCl4 during metalorganic chemical vapor deposition (MOCVD) on patterned GaAs substrates. The lateral growth rate shows a linear dependence on CCl4 flow rate. On the other hand, the GaAs vertical growth rate is relatively insensitive to the CCl4 flow rate. The maximum ratio of lateral to vertical growth rate is about 14. Using these characteristics, we have fabricated CCl4-doped quantum wires (QWRs) on V-groove structures. The QWR structures show thickness enhancement factors, defined as the ratio of QWR thickness in the center region to the quantum well thickness in the nonpatterned region, as high as 5.6.

Lateral growth rate of GaAs is remarkably increased with supplying CBr4, which has been utilized as a p-type dopant source for carbon doped GaAs epilayers during metalorganic chemical vapor deposition growth. The lateral growth rate can be represented as a linear function of the CBr4 flow rate, while the GaAs vertical growth rate is relatively insensitive to the CBr4 flow rate. The maximum ratio of the lateral to vertical growth rate by CBr4 is about 29. With increasing the growth temperature, the lateral growth rate increases, but it decreases at a more elevated growth temperature than 700 °C. These results are also compared to the previous results obtained by CCl4. In all cases the lateral growth rate increments by CBr4 are larger than those by CCl4.

No abstract