Impact of doping on the performance of p-type Be-doped Al0.29 Ga0.71As Schottky diodes

The effects of changing the acceptors concentration on the electrical characteristics of Au/Ti on Be-doped Al_0.29Ga_0.71As Schottky contact have been investigated in the temperature range of 100—400 K. Using three devices with three different doping levels, the barrier height (Φ_B), ideality factor (n) and series resistance (R_S) for each diode were evaluated using both thermionic emission (TE) theory and Cheung's method. Our experimental results showed that the sample with a moderate doping concentration of 3 · 10¹⁶ cm^-3 has the best performance, including ideality factor of 1.25 and rectification ratio of 2.24 · 10³ at room temperature. All samples showed an abnormal behavior of reducing Φ_B and increasing n with increase of temperature. This behavior was attributed, in case of low concentration samples, to barrier inhomogeneity and was explained by assuming a Gaussian distribution of barrier heights at the interface. While for the heavily doped sample, such non-ideal manner was ascribed with tunneling through the field emission (FE) mechanism.

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