Barrier Characteristics Of Gold Schottky Contacts On Moderately Doped N-inp Based On Temperature Dependent I-v And C-v Measurements

摘要

The temperature dependences of current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the gold Schottky contacts on moderately doped n-InP (Au/MD n-InP) Schottky barrier diodes (SBDs) have been systematically investigated in the temperature range of 60-300 K. The main diode parameters, ideality factor (n) and zero-bias barrier height (apparent barrier height) (Φ_(b0)~j) were found to be strongly temperature dependent and while the Φ_(b0)~j decreases, the n and the (Φ_b~c) increase with decreasing temperature. According to Thermionic Emission (TE) theory, the slope of the conventional Richardson plot [In(J_0/ T~2) vs. 1000/T] should give the barrier height. However, the experimental data obtained do not correlate well with a straight line below 160 K. This behaviour has been interpreted on the basis of standard TE theory and the assumption of a Gaussian distribution of the barrier heights due to barrier inhomogene-ities that persist at the metal-semiconductor interface. The linearity of the apparent barrier height (Φ_(b0)~j) vs. 1/(2kT) plot that yields a mean barrier height (Φ_(b0)~j) of 0.526 eV and a standard deviation (σ_(s0)) of 0.06 eV, was interpreted as an evidence to apply the Gaussian distribution of the barrier height. Furthermore, modified Richardson plot [In(J_0/T~2) - (q~2σ_(s0)~2/2 k~2T~2) vs. 1/T] has a good linearity over the investigated temperature range and gives the Φ_(b0)~j and the Richardson constant (A~*) values as 0.532 eV and 15.90 AK~(-2)cm~(-2), respectively. The mean barrier heights obtained from both plots are appropriate with each other and the value of A~* obtained from the modified Richardson plot is close to the theoretical value of 9.4 AK~(-2)cm~(-2) for n-lnP. From the C-V characteristics, measured at 1 MHz, the capacitance was determined to increase with increasing temperature. C-V measurements have resulted in higher barrier heights than those obtained from I-V measurements. The discrepancy between Schottky barrier heights (SBHs) obtained from I-V and C-V measurements was also interpreted. As a result, it can be concluded that the temperature dependent characteristic parameters for Au/MD n-InP SBDs can be successfully explained on the basis of TE mechanism with Gaussian distribution of the barrier heights.