Double barrier heights in 5,6,11,12-tetraphenylnaphthacene (rubrene) based organic Schottky diode

• Rubrene were grown on p type Si (1 0 0) substrate using spin coating technique.
• We have fabricated an Al/rubrene/p-Si Schottky device.
• The electrical properties of the device have been reported in the temperature range from 75 to 300 K.
• Characteristics are analyzed on the assumption of double Gaussian distribution of barrier heights.
• Richardson constant of 33.85 for 175–300 K is very close to the theoretical value of 32 A cm−2 K−2.

5,6,11,12-Tetraphenylnaphthacene (rubrene) was grown on p type Si (100) substrate using spin coating technique. We have fabricated an Al/rubrene/p-Si Schottky device and measured the current–voltage (I–V) characteristics in the temperature range from 75 to 300 K by steps of 25 K. An abnormal decrease in the experimental barrier height ΦBΦB and an increase in the ideality factor n with a decrease in temperature have been observed. The I–V   characteristics of Al/rubrene/p-Si Schottky diode are analyzed on the basis of thermionic emission (TE) theory and the assumption of double Gaussian distribution of barrier heights due to barrier inhomogeneities. The modified Richardson plots of ln(I0/T2)−(1/2)(qσs0(i)/kT)2 versus 1000/T1000/T gives Φ¯B0(i) and AR(i) values as 1.186 and 0.571 eV, and 33.85 and 84.63 A cm−2 K−2, respectively. The modified Richardson constant value of AR(2)=33.85 A cm−2 K−2 for high temperature range (175–300 K) is very close to the theoretical value of 32 A cm−2 K−2 for p-Si.