文档介绍：6HPLRQGXWRUODVHUV
Electronic band structure conduction band
(
allowed energy band J
(Q
valence
band
(Q
forbidden energy gap Conductor Insulator
(Q
(Q conduction band
(J a² H9
Isolated atoms N atoms in a
crystalline solid valence
band
9 RXWHU HOHWURQVVKDUHWKHZKROHU\VWDOYROXPH
9 3DXOLH[OXVLRQSULQLSOH Semiconductor
9 QRWZRHOHWURQVLQWKHVDPHTXDQWXPVWDWH
6HPLRQGXWRUODVHUV
Semiconductors
2SWLDODQGHOHWULSURSHUWLHVRIVHPLRQGXWRUVDQEHHQJLQHHUHGRYHUZLGHUDQJHV
&RQGXWLYLW\
9 EDQGJDS
9 GRSLQJ
+HWHURVWUXWXUHV
9 /D\HUHGVHPLRQGXWRUVWUXWXUHV
9 ,PSRUWDQWSKRWRQLVPDWHULDOV
9 =,$OIHURY+.URHPHU 1REHO3ULHLQ3K\VLV
III – V semiconductors
DONORS ACCEPTORS
conduction band conduction band
(J (J
valence valence
band band
6HPLRQGXWRUODVHUV
Direct band-gap materials
UHRPELQDWLRQ
DQQLKLODWLRQRIHOHWURQDQGKROH
9 'LUHWEDQGJDS ,,,9 DQGVRPH ,,9, RPSRXQGV
*D$V$O*D$V,Q*D$V,Q*D$V3
UDGLDWLYHUHRPELQDWLRQ IVSRQWDQHRXVHPLVVLRQ
highly doped highly doped →/('
n-type semiconductor p-type semiconductor
9 ,QGLUHWEDQGJDS 6L*H
QRQUDGLDWLYHUHRPELQDWLRQ KHDW
9 +LJKGRSLQJRQHQWUDWLRQ ODUJHXUUHQWGHQVLW\
→ DSKRWRQDQVWLPXODWH UHRPELQDWLRQ
IVWLPXODWHGHPLVVLRQ
→ GLRGHODVHU
bination
6HPLRQGXWRUODVHUV
pn-junction NO VOLTAGE FORWARD BIAS VOLTAGE APPLIED
CONDUCTION BAND
Eg
holes FERMI ENERGY
electrons
holes h ν
electrons
Eg
VALENCE BAND
p-type n-type p-type n-type
junction junction
Laser semiconductor semiconductor semiconductor semiconductor
action
)RUZDUGELDVLQJ→´SRSXODWLRQLQYHUVLRQµ
6WLPXODWHGUHRPELQDWLRQ→ OLJKWDPSOLILDWLRQ
Light output Light
LED :LGWKRIWKHUHRPELQDWLRQ]RQH MXQWLRQZLGWK aµP
operation ,QGH[RIUHIUDWLRQRIVHPLRQGXWRUPDWHULDOVQ a
→ 5aDWGLRGHDLULQWHUIDH HQRX