p^＋–n^-–n^＋-type power diode with crystalline/nanocrystalline Si mosaic electrodes

Using p~+-type crystalline Si with n~+-type nanocrystalline Si(nc-Si) and n~+-type crystalline Si with p~+-type nc-Si mosaic structures as electrodes,a type of power diode was prepared with epitaxial technique and plasmaenhanced chemical vapor deposition(PECVD) method.Firstly,the basic p~+-n~--n~+-type Si diode was fabricated by epitaxially growing p~+- and n~+-type layers on two sides of a lightly doped n~--type Si wafer respectively.Secondly,heavily phosphorus-doped Si film was deposited with PECVD on the lithography mask etched p~+-type Si side of the basic device to form a component with mosaic anode.Thirdly,heavily boron-doped Si film was deposited on the etched n~+-type Si side of the second device to form a diode with mosaic anode and mosaic cathode.The images of high resolution transmission electronic microscope and patterns of X-ray diffraction reveal nanocrystallization in the phosphorus- and boron-deposited films.Electrical measurements such as capacitancevoltage relation,current-voltage feature and reverse recovery waveform were carried out to clarify the performance of prepared devices.The important roles of(n~-)Si/(p~+)nc-Si and(n~-)Si/(n~+)nc-Si junctions in the static and dynamic conduction processes in operating diodes were investigated.The performance of mosaic devices was compared to that of a basic one.