Learning Outcomes

At the end of this course, (I hope) students will be able to:

1. Calculate conduction properties of materials and simple device structures.
2. Explain the operating principles of semiconductor diodes, bipolar junction transistors, field-effect transistors, light-emitting diodes, laser diodes and solar cells.
3. Determine the electrical characteristics of the devices mentioned in 2.
4. Perform electrical measurements of the devices mentioned in 2.
5. Use a spreadsheet program, such as Excel or Origin, to model and plot the electrical chracteristics of the devices mentioned in 2—given bias conditions.
6. Calculate the model parameters and draw circuit models for the devices mentioned in 2.
7. Design the devices mentioned in 2 given required electrical performance.

Specific learning outcomes by chapter

Chapter 1: Electrons, Atoms and Solid States
Students are expected to be able to: (updated 2016)

• explain how the Bohr model can be used to explain the observed atomic spectra of hydrogen
• explain the differences among the Paschen, Balmer and Lyman series of hydrogen atomic spectra
• calculate electron energies when the electron is confined in a potential well, using your understanding of quantum mechanics
• explain the tunnelling mechanism
• appreciate the importance of Pauli's exclusion principle, quantum numbers and selection rules
• describe the electronic structure of atoms of important semiconductors (Si, Ge, GaAs…)
• explain the origin of energy gap
• identify the band diagram of semiconductors, metals and insulators
• explain how direct and indirect semiconductors differ, in terms of energy band diagrams and their applications.

Chapter 2: Crystal Properties and Growth of Semiconductors
Students are expected to be able to: (updated 2016)

• explain how periodic atomic arrangement influence the formation of amorphous, single-crystal and poly-crystal solids
• identify the three types of cubic lattices, diamond- and zincblende lattices
• determine the fraction of cubic lattices that can be filled with hard spheres. This reflects mechanical properties of common semiconductors
• identify/draw crystallographic planes and directions of cubic lattices
• explain the differences between, the uses of, and the process flow in the making of metallurgical grade silicon (MGS) and electronic grade silicon (EGS)
• identify the type of impurity and the amount needed in the growth of silicon ingots with certain electrical requirements
• explain the reasons behind the needs for heroepitaxy and issues related to lattice matching in epitaxial growth
• understand the operating principles of the various epitaxial techniques (VPE, LPE and MBE).

Chapter 3: Carriers
Students are expected to be able to: (updated Jun 2013)

• describe the origin and properties of carriers (electrons and holes)
• distinguish between i) intrinsic and extrinsic semiconductors, ii) minority and majority carriers
• understands carrier processes in semiconductor under equilibrium vs steady-state conditions
• determine equilibrium carrier concentrations (n₀, p₀) of intrinsic and extrinsic semiconductors (mass action law)
• …and qualitatively explain the changes as a function of temperature
• describe the differences between equilibrium carriers (n₀, p₀) and excess carriers (dn, dp)
• …and quantitatively explain the changes as functions of space and time
• use the energy band diagrams to describe intrinsic and extrinsic semiconductors, both under equilibrium and steady-state conditions
• explain the mechanisms related to excess carriers generation and recombination
• explain the differences between i) direct and indirect recombination, ii) recombination centers and traps

Chapter 4: Carrier Transports
Students are expected to be able to: (updated Jun 2013)

• explain how carriers (electrons & holes) are transported in a semiconductor, or in a circuit under bias
• explain the cause and effects of carrier drift in a semiconductor under external electric field. Specifically,
• how carrier mobilities (m_n and m_p) vary with temperature, doping concentration
• how resistivity and conductivity vary with temperature, doping concentration
• what happens to carriers when the electric field is very strong
• explain the cause and effects of carrier diffusion in a semiconductor
• determine whether a semiconductor is under an electric field (dV/dx) and/or concentration gradients (dn/dx, dp/dx) given bias, doping, excitation conditions
• determine current density due to carriers drift and/or diffusion
• explain the relationship between drift (m) and diffusion (D)—the Einstein relation—and use it to determine D given m, and vice versa
• use the continuity equations to solve specific problems that yield solutions which are i) time-dependent only, or ii) space-dependent only

Chapter 5: Junctions
Students are expected to be able to: (updated July 2013)

• for p-n junctions without bias (equilibrium):
• calculate the built-in potential (V_o), depletion width (total W, on the n-side x_n, and on the p-side x_p)
• draw the band diagram, the distributions of charge density r(x) and electric field x(x) across the junction, and
• determine the net charge on both sides of the space charge region (Q_n, Q_p) and maximum electric field (x_max)
• for p-n junctions under bias (steady state):
• draw the band diagram, the minority carrier distributions [on the p-side dn(x), on the n-side dp(x)]
• explain how the diode equation can be derived
• state all the current components (diff/drift of e/h) which constitute the total diode current
• use the diode equation to determine the diode current at a given bias
• calculate a junction breakdown voltage (V_br) given a critical electric field (x_c), and vice versa
• explain the mechanisms that cause reverse bias breakdown: Zener and Avalanche
• for p-n junctions under changing bias (transients):
• plot the current-time signal (I-t) which describes the changes in current passing through a junction in a simple diode circuit where the diode is driven by a square wave
• understand the origin of the delay
• for metal-semiconductor junctions:
• draw the band diagram of the junction and, given relative values of metal and semiconductor work functions, indicate whether the junction forms a rectifying or non-rectifying (ohmic) contact
• describe the origins and consequences of the elements which appear in a diode’s equivalent circuit: what they are and their values, can they be ignored (if so under what conditions), how would they affect dc bias and ac signal
• design a p-n junction structure given required electrical performance

Chapter 6: Bipolar Junction Transistors (BJTs)
Students are expected to be able to: (updated July 2013)

• for BJTs without bias (equilibrium):
• draw the band diagram, the distributions of charge density r(x) and electric field x(x) across the BJTs
• for BJTs under bias (steady state):
• state the biassing conditions (V_EB, V_BC) of the four modes: forward-active, reverse-active, cut-off and saturation
• understand the signal paths in and out (and the related current gain) of BJTs under the common-base (a), common-emitter (b), and common-collector configurations
• explain all the current components (diff/drift of e/h) which constitute the transistor currents under forward-active and reverse-active conditions of both the npn and pnp BJTs
• draw the band diagram, the minority carrier distributions
• calculate the terminal currents (I_E, I_C, I_B) of a BJT in the forward-active mode
• for BJTs under changing bias (transients):
• plot the output current-time signal (I_C-t) given a square wave input current (I_B) and explain the cause and effect of the delay
• describe the origins and consequences of the elements which appear in a BJT’s equivalent circuit, both for large signals (Ebers-Moll model) and small signals (hybrid-p model)
• determine the transit frequency f_T of a typical BJT and a high-speed BJT
• design a BJT structure given required electrical performance

Chapter 7: Field-Effect Transistors (FETs)
Students are expected to be able to: (updated July 2013)

• for general field-effect transistor (FET) action:
• describe the basic FET structure/operation by channel types (n or p), and by the presence/absence of conduction channel under equilibrium (enhancement, depletion)
• explain the transistor action
• describe how the channel current (I_D) can be determined
• for the metal-oxide-semiconductor (MOS) structure:
• draw the band diagram across the MOS structure in equilibrium and under bias
• describe the conditions required to induce the inversion layer
• *calculate the threshold voltage (V_T) of MOS structures and explain how V_T can be controlled
• *calculate certain physical properties of a MOS structure given its C-V characteristic, and vice versa
• for MOSFETs:
• calculate the channel current (I_D) given material parameters and bias conditions
• determine whether a certain bias condition will result in MOSFET operating in the triode, saturation or cut-off condition
• draw/explain typical output and transfer characteristics of a MOSFET
• for other FETs: describe the structures and the operating principles of JFETs, MESFETs, HFETs
• describe the origins and consequences of the elements which appear in a MOSFET’s equivalent circuit,
• describe the basic scaling “rule” and the consequences for consumer electronics
• design a MOSFET structure given required electrical performance

Chapter 8: Optoelectronic Devices
Students are expected to be able to: (updated July 2013)

• select the most appropriate semiconductor for optical generation and/or detection at a specified wavelength
• explain the i) operating principles, ii) structures, and iii) electrical/optical characteristics of various optoelectronic devices:
• light-emitting diodes (LEDs)
• laser diodes (LDs); with special emphasis on the population inversion and resonant cavity
• photodetectors (bulk: photoconductors; junctions: photodiodes)
• solar cells
• describe the origins and implications of the loss and dispersion characteristics of an optical fiber.

Songphol 12 September 2016