Me kana Intrinsic Silicon da Extrinsic Silicon?

Misali Silicon da Extrinsic Silicon Suna?

Intrinsic Silicon

Silicon yana wani muhimmin elementi na semiconductor. Silicon yana cikin kungiyar IV. A cikin orbitoshin rarrabe, akwai elektronu biyu waɗanda suka fi amfani da covalent bonds tare da elektronu biyu na silicon masu jirgin. Wadannan elektronu ba za su iya amfani da shi don electricity. Saboda haka, a OoK, intrinsic silicon yana yi nasara a matsayin insulator. Idan temperature ya zama, wasu elektronu daban-daban sun fara covalent bondsu saboda thermal energy. Wannan ya bazu wani babban kofin, wanda ake kira hole, inda elektronu ta. Kuma a matsayin haka, a gaba daya da temperature mai girma da 0oK, wasu elektronu biyu na valance band suka samu energy da take iya sa zuwa conduction band kuma ta baza hole a cikin valance band. Wannan energy yana zama 1.2 eV a room temperature (yana nufin 300oK) wanda yake sama da band gap energy na silicon.

A cikin intrinsic silicon crystal, adadin holes ita ce da adadin free electrons. Saboda har elektron idan ya fara covalent bond ta baye hole a cikin bondin da ya fara. A faren temperature, electron-hole pairs suna farawa da thermal energy, kuma adadin pairs suna rufe daidai. Saboda haka, a faren temperature a cikin volume na musamman, adadin electron-hole pairs ta zama sama. Wannan yana nufin equilibrium condition. Saboda haka, ya zama abin da free electrons concentration n da holes concentration p suka sama, kuma wannan ita ce intrinsic charge carrier concentration (ni). Yana nufin, n = p = ni. Atomic structure ta shafi a cikin wannan.

Intrinsic Silicon a 0oK

Intrinsic Silicon a Room Temperature

Extrinsic Silicon

Intrinsic silicon zai iya zama extrinsic silicon idan an ke kisa da dopants da yawa. Idan an ke kisa da donor atom (group V elements) zai zama n-type semiconductor, kuma idan an ke kisa da acceptor atoms (group III elements) zai zama p-type semiconductor.

Idan an ke kisa da small amount of group V element a cikin intrinsic silicon crystal. Misalai na group V elements sun hada da phosphorus (P), arsenic (As), antimony (Sb) da bismuth (Bi). Suna da elektronu biyar. Idan suka displace Si atom, elektronu biyu suka yi covalent bonds tare da neighboring atoms, kuma elektronu biyu wanda ba suka yi covalent bond ya zama loosely attached to the parent atom kuma zai iya fara as free electron. Energy da take iya fara elektronu biyu shine about 0.05 eV. Wannan kind of impurity ana kira donor saboda ta contribute free electrons to the silicon crystal. Silicon yana amsa n- type ko negative type silicon saboda electrons suna da negative charge.

Fermi Energy Level ya zama closer to the conduction band a n-type silicon. Hakan, adadin free electrons ta zama mai girma da intrinsic concentration of electrons. Amma, adadin holes ta zama mai ci da intrinsic hole concentration saboda ya da kyau da recombination saboda adadin free electrons concentration mai girma. Electrons suna da majority charge carriers.

Extrinsic Silicon with Pentavalent Impurity

Idan an ke kisa da small amount of group III elements a cikin intrinsic semiconductor crystal, suka displace silicon atom, group III elements like AI, B, IN suna da elektronu uku. Elektronu uku suna yi covalent bonds tare da neighboring atoms, kuma suka bazu hole. Wannan kind of impurity atoms ana kira acceptors. Semiconductor yana amsa p-type semiconductor saboda hole yana amfani da positive charge.

Extrinsic Silicon with Trivalent Impurity

Fermi energy level a p-type semiconductors ya zama closer to the valence band. Adadin holes ta zama mai girma, kuma adadin electrons ta zama mai ci da intrinsic silicon. A p-type semiconductors, holes suna da majority charge carriers.

Intrinsic Carrier Concentration of Silicon

Idan elektron yana fara zuwa conduction band saboda thermal excitation, free carriers suna farawa a both bands, wanda suka haɗa da elektron a conduction band da hole a valence band. Concentration of these carriers yana amsa intrinsic carrier concentration. Practically a pure or intrinsic silicon crystal, adadin holes (p) da electrons (n) suka sama, kuma suka sama da intrinsic carrier concentration ni. Saboda haka, n = p = ni

Adadin these carriers yana neman da band gap energy. Don silicon, band gap energy shine 1.2 eV a 298oK, intrinsic carrier concentration in silicon ta zama mai girma saboda increase of temperature. Intrinsic carriers concentration in silicon yana amsa,

Hakan, T = temperature a absolute scale

Intrinsic carrier concentration a 300oK shine 1.01 × 1010 cm-3. Amma, previously accepted value shine 1.5 × 1010 cm-3.