Study of photoluminescence spectra of GaMnAs produced by low-temperature molecular beam epitaxy

Effect of Be codoping on the photoluminescence spectra of GaMnAs

“…For GMn sample the temperature dependence of E x is weaker than in the control GaAs. As was demonstrated in our previous study [16], the difference becomes more significant with the increase in Mn concentration for homogeneous GaMnAs. The dependence of DE x on Mn Ga concentration is also supported by the fact that precipitation of Mn acceptors into MnAs clusters, caused by high temperature annealing, reduces the difference between the temperature dependences of E x values in GaMnAs and GaAs [13].…”

“…(In fact, the hole concentration is lower than the Be acceptor concentration due to the compensation by donor-like defects, the concentration of which in GaAs-based materials grown by LT MBE is about 10 20 /cc [22]). As shown in our previous study, the doping GaAs with similar concentration of Mn notably modified the temperature dependence of DE x [13,16]. Hence, we can make a conclusion that doping GaAs with Be almost does not affect the temperature dependence of the band gap.…”

“…Peaks CX and AX are associated with recombination via carbon acceptor level (carbon is well known as the most important unintentional impurities in the MBE growth process) and Ga anti-site transition, respectively [12e15]. In the GMn sample, we have also observed a wide peak with maximum at approximately 1.425 eV, which could be attributed to recombination via Mn acceptor level [12,14,16]. The anomalously large width of this peak, in our opinion, indicates that Mn-related levels form an impurities sub-band in the band gap of GaMnAs.…”

“…1 shows the PL spectra of GMn, GB, and GMB samples and reference GaAs layer measured at 4 K. For all samples, three major PL peaks, labeled as "FX", "CX", and "AX" for transition energy 1.51 eV, 1.492 eV, and 1.462 eV, respectively, have been observed. Peak FX is interpreted as exciton-related transition [13e15] and more detailed examination showed that this peak consists of at least two closed lines at energy 1.514 and 1.510 eV, which were attributed to free excitons and donor-related exciton transitions [16]. Peaks CX and AX are associated with recombination via carbon acceptor level (carbon is well known as the most important unintentional impurities in the MBE growth process) and Ga anti-site transition, respectively [12e15].…”

Persistent photoconductivity phenomena in GaMnAs grown via molecular beam epitaxy

“…These centers could, for example, play gallium atoms in the arsenic sub-lattice (so called EL2 centers) [14][15][16], which was generated in GaAs LT MBE process with a concentration of up to 10 20 cm À3 [17] or more complicated defect complexes such as arsenic anti-site complex [18]. The presence of a high concentration of Ga anti-sites in GaMnAs layers grown via LT MBE was directly confirmed by photoluminescence [19] and quasi-forbidden X-ray reflections measurements [20]. The domination of the contribution related with deep-level ionization into the PC phenomenon in the GaMnAs also explains the dependence of DR value on the T s .…”