Skip to content
Login Register

#extrinsic semiconductor

3 public questions tagged with this topic.

Semiconductors, Types and Energy Bands

The conductivity of an extrinsic semiconductor increases due to:

**Types of semiconductors** elemental Si, Ge group IV with 4 valence electrons, compound GaAs, InP etc. Intrinsic has n_e = n_h, extrinsic doped with pentavalent donors (P, As) gives n-type excess electrons, trivalent acceptors (B, Al) gives p-type excess holes, resistivity range semiconductors 10⁻⁵ to 10⁶ Ω·m vs insulators 10¹¹ Ω·m. Doping introduces impurities (pentavalent or trivalent) that provide additional charge carriers (electrons or holes), significantly enhancing conductivity compared to intrinsic semiconductors. Substituting values gives Addition of impurities, which matches expecte

Ref: NCERT > Physics Book > Electronic Devices > Semiconductors, Types and Energy Bands

View Details
Doping, Charge Carriers and Conductivity

In an extrinsic semiconductor, the minority carrier concentration is reduced due to:

**Doping** is adding impurity to pure semiconductor to increase carriers, pentavalent (P, As, Sb) donates extra electron, 1 ppm doping in Ge with 4×10²⁸ atoms/m³ gives donor density N_d = 4×10²⁸×10⁻⁶ =4×10²² m⁻³ for 1 ppm, acceptor atoms p-type trivalent B, Al, Ga. Overall charge neutrality maintained because donor ion core positive but electron negative, net neutral. Doping increases majority carriers (electrons in n-type, holes in p-type), enhancing recombination with minority carriers, thus reducing their concentration indirectly. Substituting values gives Increased recombination, which mat

Ref: NCERT > Physics Book > Electronic Devices > Doping, Charge Carriers and Conductivity

View Details
Semiconductors, Types and Energy Bands

In an extrinsic semiconductor, the overall charge neutrality is maintained because:

**Types of semiconductors** elemental Si, Ge group IV with 4 valence electrons, compound GaAs, InP etc. Intrinsic has n_e = n_h, extrinsic doped with pentavalent donors (P, As) gives n-type excess electrons, trivalent acceptors (B, Al) gives p-type excess holes, resistivity range semiconductors 10⁻⁵ to 10⁶ Ω·m vs insulators 10¹¹ Ω·m. The charge of additional carriers (electrons in n-type or holes in p-type) is balanced by the equal and opposite charge of ionized dopant cores (positive in n-type, negative in p-type). Substituting values gives Charge of carriers equals that of ionized cores, whi

Ref: NCERT > Physics Book > Electronic Devices > Semiconductors, Types and Energy Bands

View Details