Title :
Effect of deep-trap level on transverse acoustoelectric voltage measurements
Author :
Palma, Fabrizio ; De Cesare, Giampiero ; Abbate, Agostino ; Das, Pankaj
Author_Institution :
Dipartmento di Elettronica, Roma Univ., Italy
Abstract :
The effect of trapped charges on the transverse acoustoelectric voltage (TAV) is investigated with the aim of extending the use of TAV measurements to the study of semiconductors with high defect density. Even if surface acoustic wave frequencies are as high as 100 MHz, charge trapping can influence the TAV. This has been verified by two particular experiments performed on Si/SiO/sub 2/ structures with high density of interface states. A theoretical model is proposed to explain the effects of the presence of deep-trap levels on the TAV. Novel boundary conditions for the acoustoelectric equations are introduced and an approximate solution for the TAV amplitude is presented. The model is used to define a novel procedure for the determination of interface-states´ density using TAV versus bias voltage measurements.<>
Keywords :
acoustoelectric effects; deep levels; electronic density of states; elemental semiconductors; interface electron states; semiconductor technology; semiconductor-insulator boundaries; silicon; silicon compounds; surface acoustic waves; voltage measurement; 100 MHz; Si-SiO/sub 2/ structure; TAV amplitude; acoustoelectric equations; approximate solution; bias voltage measurements; boundary conditions; deep trap level effect; deep-trap levels; high defect density semiconductors; interface states density; surface acoustic wave frequencies; theoretical model; transverse acoustoelectric voltage; trapped charge effects; Acoustic measurements; Acoustic waves; Boundary conditions; Current measurement; Density measurement; Equations; Frequency; Interface states; Surface acoustic waves; Voltage;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
