Improved structure and performance of the GaAsSb/InP interface in a resonant tunneling diode

Growth of an InGaAs/GaAsSb tunnel junction for an InP-based low band gap tandem solar cell

“…The peak at 4.2 eV in the GaAsSb reference spectrum was also observed in both spectra, but shifted to 3.8 eV. In all cases the LEED patterns showed a clear cð4 Â 4Þ reconstruction as it was expected for the Asrich GaAsSb surface [14]. In Fig.…”

“…Both GaAsSb surfaces were As-terminated. Even for the Sb-terminated GaAsSb surface grown on Asrich InGaAs the Sb to As ratio was lower than for the standard As-rich GaAsSb [14], grown on III-rich InGaAs.…”

“…Compared to an As-rich GaAs 0:51 Sb 0:49 surface of a standard 300 nm layer [14], the Sb to As ratio was still lower, supposably due to contributions to the XPS signal of the As-containing InGaAs layer underneath. The lower In to Ga ratio additionally supports the assumption that the GaAsSb preparation on the III-rich InGaAs surface leads to a sharper interface.…”

“…Interfaces between an Sb-containing layer and an Sb-free layer are known to suffer from the segregation of Sb [15,16]. The GaAsSb/InP hetero-interface, prepared with MOCVD was already investigated before [14,17]. Two different types of GaAsSb surface reconstructions had been observed: an As-rich cð4 Â 4Þ and an Sb-rich ð1 Â 3Þ-like.…”

“…The investigations in Refs. [14,17] were made for an GaAsSb/InP interface grown at 500 C. In our case the InGaAsP top cell must be grown at 600 C on top of the InP layer. There are different options of the preparation routes differing in the growth temperature of the GaAsSb and InP layer.…”