Hexagonal Si-Ge Class of Semiconducting Alloys Prepared by Using Pressure and Temperature.

Multi-anvil and laser-heated diamond anvil methods have been used to subject Ge and Si mixtures to pressures and temperatures of between 12 and 17 GPa and 1500-1800 K, respectively. Synchrotron angle dispersive X-ray diffraction, precession electron diffraction and chemical analysis using electron microscopy, reveal recovery at ambient pressure of hexagonal Ge-Si solid solutions (P6 /mmc). Taken together, the multi-anvil and diamond anvil results reveal that hexagonal solid solutions can be prepared for all Ge-Si compositions.

Unconventional Route to High-Pressure and -Temperature Synthesis of GeSn Solid Solutions.

Ge and Sn are unreactive at ambient conditions. Their significant promise for optoelectronic applications is thus largely confined to thin film investigations. We sought to remove barriers to reactivity here by accessing a unique pressure, 10 GPa, where the two elements can adopt the same crystal structure (tetragonal, 4/) and exhibit compatible atomic radii.

An Unexpected Cubic Symmetry in Group IV Alloys Prepared Using Pressure and Temperature.

The cubic diamond (Fd m) group IVA element Si has been the material driver of the electronics industry since its inception. We report synthesis of a new cubic (Im m) group IVA material, a GeSn solid solution, upon heating Ge and Sn at pressures from 13 to 28 GPa using double-sided diamond anvil laser-heating and large volume press methods. Both methods were coupled with in situ angle dispersive X-ray diffraction characterization.