Bis(isopropyl­ammonium) tetra­sulfido­molybdate(VI)

The title compound, (C3H10N)2[MoS4], was synthesized by passing a rapid stream of H2S into an aqueous isopropyl­amine solution of molybdic acid. The title compound is isotypic with the corresponding W analogue (C3H10N)2[WS4]; its structure consists of a slightly distorted tetra­hedral [MoS4]2− dianion and two crystallographically independent isopropyl­ammonium cations, with all atoms located in general positions. The cations and anion are linked by weak N—H⋯S and C—H⋯S inter­actions, the strength and number of which can explain the observed Mo—S bond distances

Design requirements for group-IV laser based on fully strained Ge1-xSnx embedded in partially relaxed Si1-y-zGeySnz buffer layers

Theoretical calculation using the model solid theory is performed to design the stack of a group-IV laser based on a fully strained Ge1-xSnx active layer grown on a strain relaxed Si1-y-zGeySnz buffer/barrier layer. The degree of strain relaxation is taken into account for the calculation for the first time. The transition between the indirect and the direct band material for the active Ge1-xSnx layer is calculated as function of Sn content and strain. The required Sn content in the buffer layer needed to apply the required strain in the active layer in order to obtain a direct bandgap material is calculated. Besides, the band offset between the (partly) strain relaxed Si1-y-zGeySnz buffer layer and the Ge1-xSnx pseudomorphically grown on it is calculated. We conclude that an 80% relaxed buffer layer needs to contain 13.8% Si and 14% Sn in order to provide sufficiently high band offsets with respect to the active Ge1-xSnx layer which contains at least 6% Sn in order to obtain a direct bandgap