Type-II band alignment, a suitable direct gap (1.519 eV), superior optical-absorption (∼105) and a broad spectrum make the GeSe/SnS heterobilayer a promising material for photovoltaic applications.
ABSTRACTIt has been a challenge to inject dopant atoms onto diamond lattice sites by ion implantation, because of the complications of ion damage and defect clustering during annealing. We re-investigated this topic by implanting boron ions into an insulating natural diamond ( type II-A ) which was predamaged by carbon ion implantation. Both of the implantations were performed at liquid nitrogen temperature. The amount of pre-damage was adjusted to produce enough vacancies and interstitials in diamond to promote boron substitutionality during subsequent annealing. Samples were characterized by optical absorption and electrical measurements. It was found that optical absorption of the implanted samples strongly depends on the post implant annealing sequence. The activation energies obtained from electrical measurements match very closely to those due to boron atoms in natural p-type diamonds. Photoconductivity measurements showed that the fraction of remaining electrically active radiation defects in the implanted and annealed samples depends on the relative fluences of boron and carbon.
The optical absorptions are calculated in an InAs/GaSb-based type II and broken-gap quantum well under applied electric field. Two absorption peaks were observed through intraband transitions within the same material layer. The absorption induced by the interlayer transition is rather weak due to the small overlap of electron and hole wavefunctions. The optical absorption can be significantly affected by the applied electric field. Our results suggest that InAs/GaSb-based type II and broken-gap QWs can be employed as two-colour photodetectors, which can be controlled by the applied electric field.
The C2N/α-Te vdW heterojunction possessed a unique type-II band alignment, tunable band gap, improved optical absorption strength, and broad spectrum width (ultraviolet to near-infrared).
We demonstrate theoretically that terahertz (THz) fundamental band-gap between the electron mini-band in the InAs layer and the heavy-hole mini-band in the GaSb layer can be realized in InAs/GaSb -based type II superlattices (SLs). The THz band-gap can be tuned by varying the widths of the InAs/GaSb layers. The presence of such band-gap can result in a strong cut-off on optical absorption at THz frequencies. For typical sample structures, the THz cut-off of the optical absorption depends sensitively on temperature and a sharper cut-off can be observed at relatively high temperatures. This study is pertinent to the application of InAs/GaSb type II SLs as THz photodetectors.
Atomistic simulations of the optical absorption of type-II CdSe/ZnTe superlattices