Start here · live lab
ESE 2180 Core Concepts Lab
Five linked tabs. Change temperature or bandgap once — Fermi occupation, carrier type, and the diode Q-point all move. This is for tinkering, not for answers.
ESE 2180 · Electronic, Photonic, and Electromechanical Devices
LatticeLab
ESE 2180 · Semiconductor Physics Portal
Interactive simulations for Penn Engineering’s course on electronic, photonic, and electromechanical devices.
Start here · live lab
Five linked tabs. Change temperature or bandgap once — Fermi occupation, carrier type, and the diode Q-point all move. This is for tinkering, not for answers.
Homework studio
Homework 1 as four interactive tabs: 3D atom counting, Miller sketching, Si density + E–k transitions, and a live Fermi–Dirac smear. Later sets plug into the same sidebar.
Rotatable 3D unit cells — SC, BCC, FCC, and diamond cubic (Si) with tetrahedral covalent bonds and a live lattice-constant slider.
Maps notebook formulas for Si, GaAs, and Ge: cell volume, atomic number density, and mass density from lattice constant and basis.
Split-screen wavefunctions — a free-electron plane wave (slide 40) versus a lattice-modulated Bloch wave sitting in periodic wells (slide 41).
Direct (GaAs) vs. indirect (Si) gaps. Fire a photon at the valence-band peak and watch whether a phonon is required to conserve crystal momentum (slide 43).
Move an electron along E(k). Slope becomes group velocity, curvature becomes m*, and an electric field changes k — not the electron’s address in the silicon.
Density of states, Fermi–Dirac occupancy, and n(E)/p(E) products. Temperature smears f(E); doping slides EF and grows the electron or hole population (slides 24–26).
Open Fermi Level Visualizer · Nd, Na, TWatch an electron recombine across Eg, emit a photon, and paint the LED. Larger gap, shorter wavelength, bluer light — and a larger approximate VF.
Watch doping become a barrier, the barrier become an I–V curve, and the curve meet a resistor load line. That intersection is the only legal operating point.
Diffusion, recombination, uncovered ions, and band bending under equilibrium, forward, and reverse bias — before the circuit Q-point ever exists.
Open Junction Studio