Electrical properties and barrier modification of GaAs MIS Schottky device based on MEH-PPV organic interfacial layer Souvik Kundu, Ajit Kumar, S. Banerjee, P. Banerji n Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302, India article info Available online 26 January 2012 Keywords: Barrier height Interfacial layer GaAs MEH-PPV Photovoltaics abstract We report fabrication and electrical characterization of GaAs based metal-interfacial layer-semiconductor (MIS) device with poly[2-methoxy-5-(2 / -ethyl-hexyloxy)-1,4-phe- nylene vinylene] (MEH-PPV), as an interfacial layer. MEH-PPV raises the barrier height in Al/MEH-PPV/p-GaAs MIS device as high as to 0.87 eV. A Capacitance-Voltage (C–V) characteristic exhibits a low hysteresis voltage with an interface states density of 1.69  10 11 cm 2 eV 1 . Moreover, a high transition frequency (f c ) of about 50 kHz was observed in the accumulation mode. The photovoltaic response of Al/MEH-PPV/p-GaAs device was measured under the air masses (AM) 1.0 and 1.5. The open circuit voltage (V OC ), short circuit current (I SC ), fill factor and the efficiency of the Al/MEH-PPV/p-GaAs device were found to be 1.10 V, 0.52 mA, 0.65, and 5.92%, respectively, under AM 1.0 condition. & 2012 Elsevier Ltd. All rights reserved. 1. Introduction One of the most interesting properties of any metal– semiconductor (MS) junction is the Schottky barrier height (F BH ). A potential barrier will appear with height F BH at the metal side, which will stop the electron injection from the metal into the conduction band of the semiconductor. The value of the Schottky barrier height (SBH) is (F m  w), where F m is the metal work function, and w is the electron affinity. So, F BH is the rectifying barrier for electrical conduction across the MS junction and has a great importance to the successful operation of Schottky based semiconductor device. The magnitude of the SBH reflects the mismatch in the energy between the conduction band edge of the semiconductor and the Fermi level of the metal across the MS interface. Thermionic emission current is associated with an MS Schottky barrier diode (SBD). Barrier height controls the thermionic emission current. When barrier height increases, forward bias current decreases, however, it has some other advantages. Increase in the barrier height enhances the field emission, reduces the leakage current; and the break down voltage increases on applying the reverse bias voltage. Thus for photovoltaic and high frequency appli- cations, higher values of barrier height is preferred. On the other hand, decrease in barrier height enhances the thermionic current. Such reduced barrier height is useful for sensor applications. Obviously by barrier height engi- neering one can have precise value of the barrier so as to make a useful device for a choiceable application. Schottky barrier height can be modified by introducing a thin interlayer between the metal and semiconductor, where the interlayer may be an (i) inorganic layer, or (ii) organic layer. GaAs is one of the most promising alternative channel materials due to its higher electron mobility, low power consumption, high breakdown field and direct bandgap. In a metal–semiconductor (MS) device, parameters such as SBH and ideality factor (Z) affect the performance of the device. Al/p-GaAs metal–semiconductor (MS) Schottky device gives a small barrier height, causes a Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/mssp Materials Science in Semiconductor Processing 1369-8001/$ - see front matter & 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.mssp.2012.01.001 n Corresponding author. Tel.: þ91 3222 283984; fax: þ91 3222 255303. E-mail address: pallab@matsc.iitkgp.ernet.in (P. Banerji). Materials Science in Semiconductor Processing 15 (2012) 386–392