EGRE 303 Lab 2: Carrier Drift and Diffusion

EGRE 303 Lab 2: Carrier Drift and Diffusion Report due on 03/018/2024, Monday 11:59 pm Carrier Drift and Diffusion Project Goal: In this laboratory you will explore and understand charge carrier (both electrons and holes) transport in Si and GaAs using the Drift-Diffusion simulation tool available at nanoHUB. (nanohub.org). The Drift Diffusion Lab is included in the Assembly of Basic Applications for Coordinated Understanding of Semiconductors (ABACUS). For Lab 1, you already registered on nanoHUB. After you login, through resources tab open tools: https://nanohub.org/resources/tools In the central column “Resources” find ABACUS and launch it: https://nanohub.org/resources/abacus You will see the screen below. Select the “Drift Diffusion Lab”. By the end of this lab, you should: – Know how to use nanoHUB Drift Diffusion lab to explore carrier transport in semiconductor materials with different doping levels and at different temperatures Know how to interpret the charge carrier transport data Be able to calculate carrier mobilities and saturation velocities from current-voltage (I-V) characteristics. Understand the effects of temperature and dopant concentration on the charge carrier mobility. Be able to relate these parameters to the performance of electronic devices. Project Tasks: 1. Consider a slab of Si with length 0.1 m and run simulations at 300 K under applied bias from 0 to 2 V for doping levels of a. p-type doping at 1 × 1014 −3. b. n-type doping at 1 × 1014 −3. Make observations of the general I-V characteristics and changes with applied bias level. 1 EGRE 303 Lab 2: Carrier Drift and Diffusion Repeat your simulations for a Si slab length of 20 and study the qualitative effects of slab length on the I-V characteristics. Explain and justify all your observations. Generate the corresponding [cm/s] vs. E [V/cm] curves for holes and electrons from the simulations above. Determine the saturation velocities. Explore/discuss qualitatively if and how you can extract the mobilities and from the plots you generated. Note 1: You should download the data sets (.txt file) for all graphs using the download option in the results menu or using the download button next to the results drop-down menu. You can then plot your own graphs using the program of your choice (Matlab, Excel, Origin, etc.) Note 2: In the I-V characteristics, the vertical axis is current density (A/cm2); therefore, you do not need the cross-sectional dimensions of the slab. 2. Consider a slab of Si with length 1 m and run simulations at 300 K under appropriate applied bias levels and investigate the effect of doping on charge carrier mobilities. a. Study the effect of n-type doping level on electron mobility using at least 5 different values from 1 × 1014 −3 to 1 × 1018 −3. b. Study the effect of p-type doping level on hole mobility using at least 5 different values from 1 × 1014 −3 to 1 × 1018 −3. Using the data from your simulations produce plots of vs. and vs and discuss/justify the effects of doping on mobility. 3. Consider a slab of Si with length 1 m and run simulations under appropriate applied bias levels at various temperatures from 77 K to 500 K to investigate the effect of temperature on charge carrier mobilities at different doping levels. a. Investigate the effect of temperature for each doping level in Task 2a. b. Investigate the effect of temperature for each doping level in Task 2b. Using the data from your simulations produce plots of vs. T and vs. T and discuss/justify the effects of temperature on mobility. Investigate qualitatively any potential impact of “freeze out” of carriers. Report Format: 1. Team report A single report must be submitted for the team. The report must have continuous flow without any breaks or abrupt transitions! Everything included in the report must serve a purpose! The report must reflect specifically what you learned in this lab project. Use sections such as Introduction, Methods, Results and Discussion, and Conclusions. Figures (schematics, simulation screenshots, etc.), tables, and equations (e.g. Fig. 1, Table 1, Eqn. 1) must be consecutively numbered in the order they appear and must be properly cited in the text of the report (e.g. as shown in Fig. 2 …, Table 1 tabulates …, According to Eqn. 3 …). All figures and tables must have captions. References must be provided at the end of the document and all references must be cited properly within the text. (Wikipedia is not acceptable) Equal work attestation: Reports must include a list of your team members, their individual contributions, and a signature from each member attesting that all members contributed equally to the project. 2 EGRE 303 Lab 2: Carrier Drift and Diffusion A cover page is not mandatory required; names and the lab title can be provided on the first page of the report. A single lab report must be submitted for the team. Each team member is required to submit separately an Individual Executive Summary. 2. Individual Executive Summary Each team member is required to submit an individual Executive Summary (single page). The summary should state the goals of the work in your own words, summarize the results and important findings, discuss any individual challenges faced and personal learning experience, and reflect what you learned from this lab project. Every student should write the executive summary separately and submit individually. Failure to satisfy these requirements will result in a lower grade. Report Deliverables: 1. Introduction should overview the relevance of carrier transport for the operation of different types of electronic devices, diodes, BJTs, FETs, etc., specifically mentioning dominating transport mechanisms for each of them. 2. Graphs and discussion for the effect of electrical bias and slab length on I-V characteristics and drift velocities for both types of charge carriers: electrons and holes. 3. Methods for determination of charge carrier mobilities from I-V characteristics. 4. Graphs and discussion for the effect of doping on I-V characteristics and mobilities of charge carriers. 5. Graphs and discussion for the effect of temperature on I-V characteristics and mobilities of charge carriers. Caution: Do not overlook the increase in the intrinsic carrier concentration with increasing temperature. 6. Discussion of observations in terms of different scattering mechanisms using knowledge obtained in classroom and the implications of the observed features for electronic devices based on Si and other semiconductors. 7. Discussion of any limitations of the simulation software used. 3