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Overview

This page provides concrete examples of semiconductor analysis using SemiCode Analyzer. Each example shows the input values, electron configurations, valence electron calculations, and resulting material types.

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How semiconductor doping works

Semiconductor doping involves introducing impurity atoms into a pure semiconductor crystal to modify its electrical properties:
  • Host material: Typically has 4 valence electrons (Group 14: Si, Ge)
  • N-type dopant: Has 5 valence electrons (Group 15: P, As, Sb) - provides excess electrons
  • P-type dopant: Has 3 valence electrons (Group 13: B, Al, Ga) - creates holes
  • Intrinsic: Same material or materials with matching valence electrons

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Silicon-based examples

Silicon (Si, atomic number 14) is the most common semiconductor material in electronics.

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Silicon + Phosphorus → N-type semiconductor

Input:
  • Element A (Host): 14 (Silicon)
  • Element B (Dopant): 15 (Phosphorus)
Electron configurations:Silicon (Si):
Atomic number: 14
Configuration: 1s2 2s2 2p6 3s2 3p2
Valence electrons: 4
Holes: 4
Phosphorus (P):
Atomic number: 15
Configuration: 1s2 2s2 2p6 3s2 3p3
Valence electrons: 5
Holes: 3
Result:
Material Type: Tipo N (Exceso de electrones)
Explanation: Phosphorus has 5 valence electrons. When it replaces a silicon atom in the crystal lattice, 4 electrons form covalent bonds with neighboring silicon atoms. The 5th electron is loosely bound and becomes a free charge carrier, creating an N-type (negative) semiconductor with excess electrons.Energy band diagram:
  • Fermi level shifts closer to the conduction band
  • Increased electron density in conduction band
  • Donor energy level just below conduction band
Applications:
  • N-type region in diodes and transistors
  • Solar cell contacts
  • Integrated circuit components

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Germanium-based examples

Germanium (Ge, atomic number 32) was the first widely used semiconductor material.
Input:
  • Element A (Host): 32 (Germanium)
  • Element B (Dopant): 15 (Phosphorus)
Electron configurations:Germanium (Ge):
Atomic number: 32
Configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2
Valence electrons: 4
Holes: 4
Phosphorus (P):
Atomic number: 15
Configuration: 1s2 2s2 2p6 3s2 3p3
Valence electrons: 5
Holes: 3
Result:
Material Type: Tipo N (Exceso de electrones)
Properties:
  • N-type germanium semiconductor
  • Excess electrons as charge carriers
  • Lower band gap than silicon (0.66 eV vs 1.12 eV)
  • Higher electron mobility than silicon
Applications:
  • Early transistors (1940s-1960s)
  • High-frequency devices
  • Infrared detectors
  • Modern high-speed electronics
Input:
  • Element A (Host): 32 (Germanium)
  • Element B (Dopant): 5 (Boron)
Electron configurations:Germanium (Ge):
Atomic number: 32
Configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2
Valence electrons: 4
Holes: 4
Boron (B):
Atomic number: 5
Configuration: 1s2 2s2 2p1
Valence electrons: 3
Holes: 5
Result:
Material Type: Tipo P (Exceso de huecos)
Properties:
  • P-type germanium semiconductor
  • Excess holes as charge carriers
  • Higher hole mobility than silicon
  • More temperature sensitive than silicon
Applications:
  • Point-contact transistors
  • Radiation detectors
  • Specialized applications requiring high mobility
Input:
  • Element A (Host): 32 (Germanium)
  • Element B (Dopant): 32 (Germanium)
Electron configurations:Germanium (Ge) - Host:
Atomic number: 32
Configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2
Valence electrons: 4
Holes: 4
Germanium (Ge) - Dopant:
Atomic number: 32
Configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2
Valence electrons: 4
Holes: 4
Result:
Material Type: Intrínseco (Aislante)
Properties:
  • Pure germanium semiconductor
  • Small band gap (0.66 eV)
  • Higher intrinsic carrier concentration than silicon
  • More conductive than intrinsic silicon at room temperature
Comparison with silicon:
PropertyGermaniumSilicon
Band gap0.66 eV1.12 eV
Max temperature~85°C~150°C
Electron mobility3900 cm²/V·s1400 cm²/V·s
Historical use1940s-1960s1960s-present
Input:
  • Element A (Host): 32 (Germanium)
  • Element B (Dopant): 33 (Arsenic)
Electron configurations:Germanium (Ge):
Atomic number: 32
Configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2
Valence electrons: 4
Holes: 4
Arsenic (As):
Atomic number: 33
Configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3
Valence electrons: 5
Holes: 3
Result:
Material Type: Tipo N (Exceso de electrones)
Properties:
  • N-type germanium with arsenic dopant
  • Common dopant in germanium technology
  • Similar atomic size to germanium (better lattice match than phosphorus)
  • Lower ionization energy than phosphorus in germanium
Applications:
  • Preferred N-type dopant for germanium devices
  • Better solubility in germanium than phosphorus
  • Used in modern germanium-based MOSFETs

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Understanding the calculation logic

The application determines material type using this algorithm (from src/utils/chemistry.js:40-48): 
export const determineMaterial = (el1, el2) => {
  const v1 = el1.valenceElectrons;
  const v2 = el2.valenceElectrons;

  if (v1 === 4 && v2 === 4) return "Intrínseco (Aislante)";
  if ((v1 === 4 && v2 === 5) || (v1 === 5 && v2 === 4)) return "Tipo N (Exceso de electrones)";
  if ((v1 === 4 && v2 === 3) || (v1 === 3 && v2 === 4)) return "Tipo P (Exceso de huecos)";
  return "Ninguno de los anteriores";
};
Logic breakdown:
  1. Intrinsic: Both elements have 4 valence electrons
  2. N-type: One element has 4, the other has 5 valence electrons
  3. P-type: One element has 4, the other has 3 valence electrons
  4. Invalid: Any other combination (e.g., 2+6, 3+3, 5+5)

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Invalid combinations

Not all element combinations produce valid semiconductors: 
Input: B (5) + Al (13)
Valence: 3 + 3
Result: "Ninguno de los anteriores"
Reason: No Group 14 host material

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Common dopants by group

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Group 13 (P-type dopants)

  • Boron (B): Most common, small atomic radius
  • Aluminium (Al): Alternative dopant, larger radius
  • Gallium (Ga): Used in GaAs and other III-V semiconductors
  • Indium (In): Heavier dopant, special applications

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Group 14 (Semiconductor hosts)

  • Carbon (C): Diamond semiconductors (wide band gap)
  • Silicon (Si): Most common, industry standard
  • Germanium (Ge): High mobility, specialized uses
  • Tin (Sn): Experimental semiconductor applications

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Group 15 (N-type dopants)

  • Nitrogen (N): Limited use, small radius
  • Phosphorus (P): Most common for silicon
  • Arsenic (As): Preferred for germanium, used in silicon
  • Antimony (Sb): Heavy dopant, slow diffusion

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Visualizations in the application

When you run these examples in SemiCode Analyzer, you’ll see:
  1. Electron configuration diagrams: Shows the shell structure for both elements
  2. Energy band diagram: Displays the position of the Fermi level
    • N-type: Fermi level near conduction band (top 25%)
    • P-type: Fermi level near valence band (bottom 75%)
    • Intrinsic: Fermi level in the middle (50%)
  3. Crystal lattice structure: Visual representation of atom arrangement and dopant placement

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Practical exercise

Try these combinations in the application:
  1. Si (14) + P (15) → Verify N-type output
  2. Si (14) + B (5) → Verify P-type output
  3. Ge (32) + As (33) → Verify N-type output
  4. Si (14) + Ga (31) → Verify P-type output (Gallium: 4s2 4p1, 3 valence electrons)
  5. C (6) + Si (14) → Check the result (both have 4 valence electrons)

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Further reading

To learn more about semiconductor physics and doping:

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