Nov 5, 2014

Study of barrier inhomogeneities using I–V–T characteristics of Mo/4H–SiC Schottky diode

In the present work we investigate the forward current–voltage (I–V  ) characteristics, over a wide temperature range 298–498 K, of Mo/4H–SiC Schottky diode for which aluminum ion implantation was used to create the high resistivity layer forming the guard ring. The (I–V  ) analysis based on Thermionic Emission (TE) theory shows a decrease of the barrier height ϕ  B and an increase of the ideality factor n   when the temperature decreases. These anomalies are mainly due to the barrier height inhomogeneities at the metal/semiconductor interface as we get a Gaussian distribution of the barrier heights when we plot the apparent barrier height ϕ  ap versus q  /2kT  . The mean barrier height and the standard deviation obtained values are View the MathML sourceB0=1.160 eV and σ0=88.049 mV, respectively.
However, by means of the modified Richardson plot View the MathML source versus q  /kT  , the mean barrier height and the Richardson constant values obtained are View the MathML sourceB0=1.139 eV and A  *=129.425 A/cm2 K2, respectively. The latter value of View the MathML sourceB0 matches very well with the mean barrier height obtained from the plot ofϕap versus q/2kT. The Richardson constant is much closer to the theoretical value of 146 A/cm2 K2.
The series resistance Rs is also estimated from the forward current–voltage characteristics of Mo/4H–SiC Schottky contact. This parameter shows strong temperature dependence. The T0 effect is validated for the 298–498 K temperature range for the used Schottky diode and provides a clear evidence for the barrier inhomogeneity at the Mo/4H–SiC interface. Finally, we note the impact of the implantation process as well as the choice of the used ion on the characterized parameters of the Schottky contact.

Keywords

No comments:

Post a Comment