Microsoft Word - Lab 2 - Ca
ier Drift and Diffusion.docx
EGRE 303 Lab 2: Ca
ier Drift and Diffusion
1
Report due on 10/08/2021, Friday 11:59 pm
Ca
ier Drift and Diffusion
Project Goal:
In this laboratory you will explore and understand charge ca
ier (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
esources/tools
In the central column “Resources” find ABACUS and launch
it: https:
nanohub.org
esources/abacus
You will see the screen shown. Select the “Drift Diffusion Lab”.
By the end of this lab, you should:
- Know how to use nanoHUB Drift Diffusion lab to explore ca
ier transport in semiconductor materials with
different doping levels and at different temperatures
- Know how to interpret the charge ca
ier transport data
- Be able to calculate ca
ier mobilities and saturation velocities from cu
ent-voltage (I-V) characteristics.
- Understand the effects of temperature and dopant concentration on the charge ca
ier 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 × 10 .
. n-type doping at 1 × 10 .
Make observations of the general I-V characteristics and changes with applied bias level.
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 co
esponding [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 cu
ent 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 ca
ier mobilities.
a. Study the effect of n-type doping level on electron mobility using at least 5 different values from
1 × 10 to 1 × 10 .
EGRE 303 Lab 2: Ca
ier Drift and Diffusion
2
. Study the effect of p-type doping level on hole mobility using at least 5 different values from 1 ×
10 to 1 × 10 .
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 ca
ier mobilities at
different doping levels.
a. Investigate the effect of temperature for each doping level in Task 2a.
. 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 ca
iers.
Report Format: Failure to satisfy these requirements will result in a lower grade.
1. Team Report
A single lab report must be submitted for the team. The report must have continuous flow without any
eaks or a
upt transitions! Everything included in the report must serve a purpose! The report must
eflect 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
e 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.
A cover page is not needed; names and the lab title can be provided at the top of the first page of the report.
2. Individual Executive Summary
Each team member is required to submit separately an Individual Executive Summary (single page). The
executive summary should state the goals in your own words, describe the lab project, 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.
Report Deliverables:
1. Introduction should overview the relevance of ca
ier transport for the operation of different types of electronic
devices: diodes, BJTs, FETs, etc., specifically mentioning dominant transport mechanisms for different types.
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 ca
iers: electrons and holes.
3. Methods for determination of charge ca
ier mobilities from I-V characteristics.
4. Graphs and discussion for the effect of doping on I-V characteristics and mobilities of charge ca
iers.
5. Graphs and discussion for the effect of temperature on I-V characteristics and mobilities of charge ca
iers.
Caution: Do not overlook the increase in the intrinsic ca
ier 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.