Photo-assisted Vapor Phase Epitaxy Research Articles

Photoluminescence of localized exitons in coherently strained ZnS-ZnSe/GaAs(001) quantum wells

The low-temperature photoluminescence (PL) of ZnS-ZnSe heterostructures grown in the form of single quantum wells (QW) by the non-conventional technology of photo-assisted vapor phase epitaxy has been investigated. It is shown that the inhomogeneity of the quantum wells can be explained in terms of a model based on disordering of the heterointerfaces. It is found that the mobility edge which separates the localized states from the delocalized states is 6 meV below the heavy-exciton ground state in the quantum wells with a nominal width Lz=11 A.

Optical studies of [formula omitted] single quantum wells grown by photo-assisted vapor phase epitaxy

Confinement effects of phonon and excitonic modes in two monolayers-thickness ZnSeZnS single quantum wells (SQWs) grown through photo-assisted vapor phase epitaxy (PAVPE) have been investigated by means of Raman, photoluminescence (PL) and reflection spectroscopy. It has been found that the frequency of the SQW longitudinal optical (LO) phonon mode is red shifted by 2.1 cm −1 relative to the LO phonon frequency of bulk ZnSe. This shift has been attributed to the combined opposite action of strain and confinement effects. The PL data have shown that the 1 s state of the n = 1 subband heavy-hole ( hh) excitonic band is blue shifted by 188 meV relative to the energy of free excitons in the bulk material. Largely responsible for this shift is the quantum confinement of electrons and holes. In addition, the transitions involving the 2 s state of the hh excitons have been clearly observed. The 2 s−1 s energy splitting was found to be 38 meV. From this result, the binding energy of the 1 s hh exciton has been estimated to be 44 meV.

Nitrogen doping in ZnSe by photo-assisted metalorgani vapor phase epitaxy

Doping characteristics of nitrogen in ZnSe using photo-assisted vapor phase epitaxy were investigated. The source precursors and the doping source were diethylzinc, dimethylselenide, and tertiarybutylamine. Photoluminescence, electrical properties of Schottky diodes, and electroluminescence from homo and double heterojunction diodes consistently supported p-type behavior of the ZnSe:N layers. At the conditions investigated, higher doping was achieved at lower substrate temperature and irradiation intensity; e.g., 350°C and 45 mW/ cm2, respectively. As a guideline, net acceptor concentration was estimated as 2 x 1017 cm-3 for the ZnSe:N layer with nitrogen concentration of 5 x 1017 cm-3 revealed by secondary ion mass spectroscopy.