Masu gano hoto da kuma tsawon tsayin daka

Masu daukar hotoda kuma tsawon tsayin daka

Wannan labarin ya mayar da hankali kan kayan aiki da ka'idojin aiki na masu gano hoto (musamman tsarin amsawa bisa ga ka'idar band), da kuma mahimman sigogi da yanayin aikace-aikacen kayan semiconductor daban-daban.
1. Babban ƙa'ida: Mai gano hoto yana aiki bisa ga tasirin photoelectric. Photons ɗin da suka faru suna buƙatar ɗaukar isasshen kuzari (fiye da faɗin bandgap Misali na kayan) don tayar da electrons daga band ɗin valence zuwa band ɗin conduction, suna samar da siginar lantarki da za a iya ganowa. Ƙarfin photon yana daidai da tsawon rai, don haka mai gano yana da "tsawon rai" (λ c) - matsakaicin tsawon rai wanda zai iya amsawa, wanda ba zai iya amsawa yadda ya kamata ba. Ana iya kimanta tsawon rai na yankewa ta amfani da dabarar λ c ≈ 1240/Eg (nm), inda ake auna Eg a cikin eV.
2. Muhimman kayan semiconductor da halayensu:
Silicon (Si): Faɗin bandgap na kimanin 1.12 eV, tsawon yankewa na kimanin 1107 nm. Ya dace da gano gajerun tsawon rai kamar 850 nm, wanda aka saba amfani da shi don haɗin fiber optic mai amfani da yawa na gajerun lokaci (kamar cibiyoyin bayanai).
Gallium arsenide (GaAs): Faɗin bandgap na 1.42 eV, tsawon yankewa na kimanin 873 nm. Ya dace da band na tsawon tsayi na 850 nm, ana iya haɗa shi da tushen hasken VCSEL na abu ɗaya akan guntu ɗaya.
Indium gallium arsenide (InGaAs): Ana iya daidaita faɗin bandgap tsakanin 0.36~1.42 eV, kuma tsawon yankewa yana rufe 873~3542 nm. Ita ce babban kayan ganowa don tagogi na sadarwa na fiber 1310 nm da 1550 nm, amma tana buƙatar substrate na InP kuma tana da rikitarwa don haɗawa da da'irorin da aka dogara da silicon.
Germanium (Ge): mai faɗin bandgap na kimanin 0.66 eV da kuma tsawon katsewa na kimanin 1879 nm. Zai iya rufe 1550 nm zuwa 1625 nm (L-band) kuma ya dace da abubuwan silicon, wanda hakan ya sa ya zama mafita mai yiwuwa don faɗaɗa martani ga dogayen madaukai.
Haɗin silicon germanium (kamar Si0.5Ge0.5): faɗin bandgap na kimanin 0.96 eV, tsawon yankewa na kimanin 1292 nm. Ta hanyar yin amfani da germanium a cikin silicon, za a iya tsawaita tsawon amsawa zuwa tsayin madaukai akan silicon substrate.
3. Haɗin yanayin aikace-aikace:
Band 850 nm:Masu gano hotunan siliconko kuma ana iya amfani da na'urorin gano hoto na GaAs.
1310/1550 nm band:Masu gano hotunan InGaAsgalibi ana amfani da su. Masu gano ƙwayoyin germanium ko silicon germanium alloy suma suna iya rufe wannan kewayon kuma suna da fa'idodi masu yuwuwa a cikin haɗakar da aka yi da silicon.

Gabaɗaya, ta hanyar manyan manufofin ka'idar band da kuma tsawon tsayin daka, an sake duba halayen aikace-aikace da kewayon ɗaukar nauyin tsawon tsayi na kayan semiconductor daban-daban a cikin na'urorin gano hoto, kuma an nuna alaƙar kusanci tsakanin zaɓin abu, tagar tsawon sadarwa ta fiber optic, da farashin tsarin haɗin kai.