Presentation : STM/STS Techniques
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The project aims to develop the infrastructure for scanning tunneling spectroscopy (STS) through a two-pronged approach, successfully demonstrating STS on various samples. It details the essential integration of a lock-in amplifier with a scanning tunneling microscope, challenges related to noise in density of states measurements, and presents experimental data. The document provides images and data sets acquired during the project, highlighting the effectiveness of the measurement techniques used.
Presentation : STM/STS Techniques
- 1. LDOS measurement using STM/STS techniques Chintalagiri Shashank Y5157 Outline Abstract STS LDOS Measurements Experimental Setup Images STS Data Lock-In Amplifiers Block Diagram Algorithm LDOS measurement using STM/STS techniques M.Sc. Experimental Project Chintalagiri Shashank Y5157 April 26, 2012 Chintalagiri Shashank Y5157 LDOS measurement using STM/STS techniques
- 2. LDOS measurement using STM/STS techniques Chintalagiri Shashank Y5157 Outline Abstract STS LDOS Measurements Experimental Setup Images STS Data Lock-In Amplifiers Block Diagram Algorithm 1 Abstract 2 STS LDOS Measurements Experimental Setup Images STS Data 3 Lock-In Amplifiers Block Diagram Algorithm Chintalagiri Shashank Y5157 LDOS measurement using STM/STS techniques
- 3. LDOS measurement using STM/STS techniques Chintalagiri Shashank Y5157 Outline Abstract STS LDOS Measurements Experimental Setup Images STS Data Lock-In Amplifiers Block Diagram Algorithm Abstract The goal of the project is to develop the infrastructure and expertise necessary for Scanning Tunneling Spectroscopy (STS). Taking a two pronged approach, we have moved closer to this goal and qualitatively demonstrated the ability to perform STS on various samples. The principle infrastructure necessary for this activity, specifically a lock-in amplifier, and its integration with an STM not designed for STS is described. Various sets of data acquired, indicators of the fidelity of the data, and the rationale for the designs chosen are also presented. Chintalagiri Shashank Y5157 LDOS measurement using STM/STS techniques
- 4. LDOS measurement using STM/STS techniques Chintalagiri Shashank Y5157 Outline Abstract STS LDOS Measurements Experimental Setup Images STS Data Lock-In Amplifiers Block Diagram Algorithm DOS measurement using STM Density of states measurement using STM requires detecting and quatifying voltage changes below the noise floor. Theoretical limit to the energy resolution of the measurement is given by KbT, which at 4.2K corresponds to 0.36meV and at room temperature corresponds to 25meV. Practical measurement at these levels (order of 1mV) is difficult and tends to be noisy. Chintalagiri Shashank Y5157 LDOS measurement using STM/STS techniques
- 5. LDOS measurement using STM/STS techniques Chintalagiri Shashank Y5157 Outline Abstract STS LDOS Measurements Experimental Setup Images STS Data Lock-In Amplifiers Block Diagram Algorithm Experimental Setup Chintalagiri Shashank Y5157 LDOS measurement using STM/STS techniques
- 6. LDOS measurement using STM/STS techniques Chintalagiri Shashank Y5157 Outline Abstract STS LDOS Measurements Experimental Setup Images STS Data Lock-In Amplifiers Block Diagram Algorithm Images (a) Au Large Area Scan (b) Bi2Te3 Large Area Scan (c) HOPG Large Area Scan (d) Au Small Area Scan (e) Bi2Te3 Small Area Scan (f) HOPG Small Area Scan (g) Au Conductance Map (h) Bi2Te3 Conductance Map (i) HOPG Conductance Map Chintalagiri Shashank Y5157 LDOS measurement using STM/STS techniques
- 7. LDOS measurement using STM/STS techniques Chintalagiri Shashank Y5157 Outline Abstract STS LDOS Measurements Experimental Setup Images STS Data Lock-In Amplifiers Block Diagram Algorithm STS Data (j) Au I-V (k) Bi2Te3 I-V (l) HOPG I-V (m) Au dI/dV vs V (n) Bi2Te3 dI/dV vs V (o) HOPG dI/dV vs V Chintalagiri Shashank Y5157 LDOS measurement using STM/STS techniques
- 8. LDOS measurement using STM/STS techniques Chintalagiri Shashank Y5157 Outline Abstract STS LDOS Measurements Experimental Setup Images STS Data Lock-In Amplifiers Block Diagram Algorithm Lock-In Amplification Chintalagiri Shashank Y5157 LDOS measurement using STM/STS techniques
- 9. LDOS measurement using STM/STS techniques Chintalagiri Shashank Y5157 Outline Abstract STS LDOS Measurements Experimental Setup Images STS Data Lock-In Amplifiers Block Diagram Algorithm LIA Block Diagram Chintalagiri Shashank Y5157 LDOS measurement using STM/STS techniques
- 10. LDOS measurement using STM/STS techniques Chintalagiri Shashank Y5157 Outline Abstract STS LDOS Measurements Experimental Setup Images STS Data Lock-In Amplifiers Block Diagram Algorithm LIA Algorithm Chintalagiri Shashank Y5157 LDOS measurement using STM/STS techniques