Fabrication of Szed-graded Quantum Dots for PV via Picosecond Pulsed Laser Ablation

摘要

Pulsed laser deposition experiments were performed with a frequency tripled 30 ps pulse width Nd:YAG laser. The target, an undoped < 111 > Si wafer, and the substrate are contained in a vacuum chamber with a base pressure of 1 x 10~(-7) torr. Freshly cleaved mica was used as the substrates for samples studied with atomic force microscopy (AFM), while fused silica (SiO2) was used for samples studied by optical absorption. AFM measurements were performed with a DI Nanoscope III in tapping mode to avoid displacement of the nanoparticles. Particle sizes were obtained by using a 2D peak finding computer program to analyze digitized height mode images from the Nanoscope. AFM samples were made with low shot numbers so individual particles could be clearly resolved and to avoid particles stacking. Another example is also given the use of pulsed laser ablation to fabricate InAs Quantum dots with excellent stoichiometry.