SENSORS AND ACTUATORS A-PHYSICAL, cilt.199, ss.194-201, 2013 (SCI İndekslerine Giren Dergi)
In order to obtain detailed information about the current-transport mechanisms (CTMs) in the Au/(Zn-doped) PVA/n-GaAs SBDs, the forward and reverse bias current–voltage (I–V) characteristics wereinvestigated in the temperature range of 80–350 K by the steps of 30 K. The ideality factor (n) decreasesfrom 12.850 to 2.805, while the zero-bias barrier height (˚Bo) increases from 0.145 eV to 0.606 eVwith increasing temperature from 80 K to 350 K. While the n decreases, ˚Boincreases with increas-ing temperature. Such positive temperature coefficient (˛) of ˚Bois not in agreement with the negativetemperature coefficient of band gap GaAs or barrier height (BH) of ideal diode. On the other hand, thevalue of modified barrier height (=n˚Bo) decreases almost linearly with the increasing temperature as˚B(T) = (1.909–5.852 × 10−4T) eV. It is clear that this value of the BH is in good agreement with the negativetemperature coefficient of band gap of GaAs (−5.4 × 10−4eV K−1). In addition, the semi-logarithmic ln I–Vplots at low bias voltages are almost parallel for each temperature. As a result of that, its inverse slope(Eo= nkT/q = 87 meV) remained almost constant, indicating it is independent of temperature. Such behav-ior of BH can be explained by the field emission (FE) theory especially at low temperatures rather thanthermionic emission (TE) and thermionic field emission (TFE) theories. Therefore, the non-ideal behaviorof the forward-bias I–V characteristics in Au/(Zn-doped)-PVA/n-GaAs SBD was successfully explained interms of the TE mechanism with a double GD of BHs.