Density of electron state (DOS) distribution in AlN films near the Fermi level position as measured by SCLC and DLTS

Abstract

The density of electron states (DOS) distribution N(E) in thin aluminium nitride (AlN) films prepared by radio frequency (RF) sputtering, was investigated by the space charge limited current technique (SCLC) and deep level transient spectroscopy (DLTS). It was found that both methods give satisfactory quantitative agreement of the N(E) curves in common energy ranges closed to the Fermi level (E_F ). The position of the E_F with respect to the top of the valence band (E_v ) is practically independent of RF power during AlN film deposition, whereas values of N(E_F ) increase significantly with the RF power level rising. Narrow DOS peaks were detected near the E_F . The presence of the peak was attributed to Al vacancies and oxygen-related defects both in amorphous and crystalline parts of the AlN atomic structure.

Key Words:

• Aluminium nitride
• Fermi level
• Density of electron states distribution