L. O’Reilly

Room-temperature ultraviolet luminescence from γ-CuCl grown on near lattice-matched silicon

We have probed the luminescence properties of a wide-band-gap, direct band-gap optoelectronic material, grown on closely lattice-matched silicon substrates, namely, γ-CuCl on Si. This material system is compatible with current Si or GaAs-based electronic/optoelectronic technologies. Polycrystalline epitaxy of CuCl can be controlled such that it maintains an orientation similar to the underlying Si substrate. Importantly, chemical interactions between CuCl and Si are eliminated. Photoluminescence and cathodoluminescence results for CuCl, deposited on either Si (100) or Si (111), reveal a strong room-temperature Z3 excitonic emission at ∼387nm. We have developed and demonstrated the room-temperature operation of an ultraviolet electroluminescent device fabricated by the growth of γ-CuCl on Si. The application of an electrical potential difference across the device results in an electric field, which promotes light emission through hot-electron impact excitation of electron-hole pairs in the γ-CuCl. Since th...

Antimony for n-type metal oxide semiconductor ultrashallow junctions in strained Si: A superior dopant to arsenic?

The creation of stable, highly conductive ultrashallow junctions in strained Si is a key requirement for future Si based devices. It is shown that in the presence of tensile strain, Sb becomes a strong contender to replace As as the dopant of choice due to advantages in junction depth, junction steepness, and crucially, sheet resistance. While 0.7% strain reduces resistance for both As and Sb, a result of enhanced electron mobility, the reduction is significantly larger for Sb due to an increase in donor activation. Differential Hall and secondary-ion mass spectroscopy measurements suggest this to be a consequence of a strain-induced Sb solubility enhancement following epitaxial regrowth, increasing Sb solubility in Si to levels approaching 1021cm−3. Advantages in junction depth, junction steepness, and dopant activation make Sb an interesting alternative to As for ultrashallow doping in strain-engineered complementary metal-oxide semiconductor devices.

Strain‐Enhanced Activation of Sb Ultrashallow Junctions

Sheet resistance (Rs) reductions are presented for antimony and arsenic doped layers produced in strained‐Si. Results show a modest Rs reduction for arsenic layers, a result of a strain‐induced mobility enhancement, whereas for Sb, a superior lowering is observed from improvements in both mobility and activation. Tensile strain is shown to enhance the activation of dopant Sb whilst creating stable ultrashallow junctions when low‐temperature processing is employed. Our results propose Sb as a viable alternative to As for the creation of highly activated, low resistance ultrashallow junctions for use with strain‐engineered CMOS devices.