Epitaxial Growth And First Principle Calculation Of AIN/TiN/Si System

Cubic rock-salt AIN films were deposited on Si(100)substrates using TiN as buffer layers by laser molecular beam epitaxy technique,and the influences of buffer layer thickness on crystal struture,surface morpholog y,inerfacial struture,strain,optical and electrical properties were investiga ted systematically.Meanwhile,initial stage absorption,the AlN/TiN interfa ce and transformation phenomenon of AlN film were simulated using the first principle.The results are as follows:1.Hihgly orientation Cubic rock-salt AIN films were deposited on Ti N buffer layers by laser molecular beam epitaxy technique.The orientatio n relationship of films and substrate is AlN(100)[100]//TiN(100)[100]//Si(100)[100].The stress in the TiN buffer layer and the cubic AIN thin film first decreases and then increases with the increase of the buffer layer thi ckness.The rougher TiN suface morphology is,the rougher AIN suface morphology will be.A coherent interface was formed between cubic AIN film and TiN layer,and a thin strain layer was observed on TiN/Si interf ace.2.The bandgaps of cubic AIN films are in the region of 4.3?4.5eV,which decrease as the increasing of lattice distortion.The photoluminescen ce spectrum of cubic AlN film is composed of a rather intense peak at 376 nm and a broad peak at 520 nm.AlN/TiN/Si shows a good rectificati on characteristics,which implies that cubic rock-salt AIN films are p-type semiconductor.3.A1 adatoms located right above N atoms of TiN substrate shows a coherent interface.The largest adsorption energy was obtained for monolayered cubic rock-salt AIN on TiN substrate.Through the calculations of interfacial energies of all the candidate interfaces,it was found that the cubic rock-salt AlN/TiN interface shows the smallest interfacial energy.A critical thickness2.38 nm,after which the cubic phase of AIN film transforms into its hexagonal counterpart,but neither experiment nor simulation didn't find this transition phenomenon in our work.