Chu Yun Hsiao

Incorporation of potassium at CuPc/ C60 interface for photovoltaic application

This letter demonstrates the effect of potassium (K) doping at the donor–acceptor interface of CuPc / C 60 -based organic solar cells. Power conversion efficient (PCE) doubled when a little K was doped into the CuPc / C 60 interface and the device was postannealed ( 75 ° C , 10 min). Changes in binding energies, depletion capacitance, and mobilities of electrons and holes were investigated. The marked improvement of PCE arose mostly from the increase in short-circuit current, owing to the modified charge transfer process.

Electrical Properties of Al/HfO2/n-GaN Prepared by Reactive Sputtering Method

In this study, the effects of the doping concentration of n-type GaN on Al/HfO2/GaN metal–oxide–semiconductor capacitors that incorporated sputtered HfO2 gate dielectric were determined. Electron mobility decreased and conductivity increased as doping concentration increased. The FWHM of the X-ray rocking curves of GaN(0002) also increased with doping concentration. A positively shifted and stretched capacitor–voltage (C–V) curve relative to the ideal one was obtained. Accumulation capacitance increased slightly as doping concentration increased, increasing the dielectric constant and effective oxide thickness. A moderately doped sample (ND~2 ×1018) with the lowest flat-band voltage shift (~1.6 V) showed the least stretched C–V curve, and the lowest effective oxide charge (3.2 ×1012 cm-3) and interface density (1.2 ×1012 cm-2) among the studied samples. Results of this study significantly contribute to the development of GaN-based metal–oxide–semiconductor field-effect transistors (MOSFETs) or metal–oxide–semiconductor heterojunction field-effect transistors (MOSHFETs).

Self-assembled Si/SiO2 superlattice in Si-rich oxide films

This work involves as-prepared SiOx ( x ≤ 2 ) films that were deposited by reactive sputtering. The regular Si/SiO2superlattices were self-assembled without post-annealing. The periodicity of Si/SiO2superlattices was modulated by varying the oxygen flow rate and was associated with x in SiOx in the range 2–1.3. Si/SiO2superlattices were formed under compressive stress and the factors that governed the periodicity were discussed.