Schottky Behaviour of the Cadmium Telluride Quantum Dots Fabricated by a Simple Drop Casting Method

This chapter emphasizes the Schottky behaviour of the Cadmium Telluride (CdTe) quantum dots (QDs) fabricated by a simple drop casting method. The CdTe QDs have been synthesized by the Single Injection Hydrothermal (SIH) method and the QDs are collected for 30 minutes of synthesis duration. The Powder X-ray Ray Diffraction (PXRD) data reveals the hexagonal crystal structure of particle size is 6.83 nm 30 mins CdTe QDs. The TEM images clearly divulge the crystalline nature and systematic array of the QDs. The elemental composition of the CdTe QDs is confirmed by the EDAX spectra. The van der Pauw Hall measurement clearly indicates the higher mobility of the QDs and also the p-type conductivity. The Schottky diode behaviour of the as synthesized CdTe QDs is understood from the I-V characteristics of the fabricated diode.

Aims: To synthesize the cadmium telluride quantum dots by using single injection hydrothermal method. The fundamental characterization techniques like PXRD, TEM image and EDAX spectrum are performed on the quantum dot study the structural, morphological and elemental composition. The electrical parameters and type of conductivity are studied by using the van der Pauw Hall measurement. The quantum diode is fabricated using a very simple drop casting technique and its Schottky behaviour is studied.

Study Design: Synthesis, Characterization, Fabrication and characterization of the CdTe QDs diode.

Place and Duration of Study: Synthesis: Department of Physics, Fabrication: Department of Physics. Characterizations: CeNSE, Indian Institute of Science, Bangalore

Methodology: The two sets of CdTe QDs have been synthesized. The QDs are further applied for different characterizations. The fabricated diode was subjected to study its I-V characteristics.

Results: The CdTe QDs synthesized by single injection hydrothermal method are considered for the fabrication of a diode. Before the drop cast fabrication of CdTe QDs diode, fundamental characterizations like PXRD, TEM image, EDAX spectrum The QDs diode is fabricated by drop casting method of CdTe QDs on to ITO glass substrate. Linear I-V characteristics of the QDs diode signifies the good interconnection established between the Quantum dots and reduced GB defects. From the I-V characteristics it is found that, a diode fabricated using CdTe QDs of 30 minutes synthesis exhibit good Schottky. The higher ideality factor indicates the non-thermionic emission responsible for the diode performance. This makes it here prominent to mention that a very simple synthesis and fabrication technique can be employed to study the diode. This also illustrates that the only simple and very less expensive laboratory set ups can be employed to fabricate a diode based on CdTe QDs.

Conclusion: A very simple and yet an effective method of synthesis of CdTe QDs has been emphasized. The hexagonal crystalline structure of the CdTe QDs elaborated here possess neat arrangement of the QDs which is observed from the TEM image. The electrical parameters measured show the p-type conductivity. The fabricated diode exhibits Schottky behaviour when studied for its I-V characteristics.