Rashin ruwa (ƙaddamarwa)

Rashin ruwa (ƙaddamarwa)
Bayanai
Ƙaramin ɓangare na	thin-film deposition (en)

Rashin zafi a cikin jirgin ruwa mai zafi

Evaporation wata hanya ce ta yau da kullun ta sanya Fim mai laushi. Abubuwan da suka samo asali suna narkewa a cikin iska. Rashin iska yana ba da damar barbashi na tururi suyi tafiya kai tsaye zuwa abin da aka yi niyya (substrate), inda suka taru zuwa wani yanayi mai ƙarfi. Ana amfani da evaporation a cikin microfabrication, da kuma yin samfuran macro-scale kamar fim din filastik na ƙarfe.

Tarihi

An fara lura da zubar da ruwa a cikin fitila mai haske a ƙarshen karni na sha tara. Matsalar baƙar fata ta kasance daya daga cikin manyan cikas ga yin kwararan fitila mai tsawon rai, kuma sun sami babban binciken da Thomas Edison da kamfanin General Electric ya yi, da kuma wasu da yawa da ke aiki a kan nasu fitilun. An fara daidaita wannan sabon abu ne ga tsarin zubar da iska ta Pohl da Pringsheim a cikin 1912. Koyaya, ba ta sami amfani sosai ba har zuwa shekarun 1930, lokacin da mutane suka fara gwaji tare da hanyoyin yin madubai masu rufi na aluminum don amfani a cikin telescopes. Aluminum ya kasance mai saurin amsawa da ba za a iya amfani da shi ba a cikin sinadarin sinadarai ko hanyoyin lantarki. John D. Strong ya yi nasara wajen yin madubi na farko na aluminum a cikin shekarun 1930 ta amfani da ajiyar evaporation. Saboda yana samar da murfin amorphous (gilashi) maimakon murfin crystalline, tare da daidaito mai girma da kuma kula da kauri, daga baya ya zama tsari na yau da kullun don samar da murfi mai laushi daga kayan aiki iri-iri, duka ƙarfe da wadanda ba ƙarfe ba (dielectric), kuma an karɓa don wasu amfani da yawa, kamar kayan wasa na filastik da sassan mota, samar da semiconductors da microchips, da fina-finai na Mylar tare da amfani da suka fara daga capacitors zuwa kula da sararin samaniya.

Ka'idar jiki

Tsibirin azurfa guda ɗaya da aka ajiye a saman (111) na palladium ta hanyar zafi. Substrate, duk da cewa ya sami madubi gogewa da kuma iska annealing, ya bayyana a matsayin jerin terraces. An sami daidaitattun ɗaukar hoto ta hanyar bin diddigin lokacin da ake buƙata don kammala cikakken monolayer ta amfani da microscopy na rami (STM) kuma daga fitowar jihohin da ke da kyau na kaurin fim na azurfa a cikin spectroscopy na photoemission (ARPES). Girman hoton shine 250 nm da 250 nm.

Evaporation ya ƙunshi matakai biyu na asali: tushen zafi yana narkewa da kayan kuma yana kwantar da hankali a kan wani abu mai sanyi wanda ke ƙasa da narkewa. Ya yi kama da sanannen tsari wanda Ruwa ya bayyana a kan murfin tukunya mai tafasa. Koyaya, yanayin gas da tushen zafi (duba "Kayan aiki" a ƙasa) sun bambanta. Ruwan kamar ruwa ba zai iya kasancewa a cikin iska ba, saboda suna buƙatar wani matakin matsin lamba na waje don riƙe atoms da kwayoyin tare. A cikin iska, kayan suna raguwa (sun bushe), suna fadada waje, kuma a kan tuntuɓar farfajiya ƙasa a cikin mai ƙarfi (ajiyewa) ba tare da wucewa ta cikin yanayin ruwa ba. Don haka, idan aka kwatanta da ruwa, tsarin ya fi kama da sanyi a kan taga.

Evaporation yana faruwa a cikin wani iska, watau tururi ban da kayan tushe kusan an cire su gaba ɗaya kafin a fara aikin. A cikin babban iska (tare da hanya mai tsawo), barbashi masu narkewa na iya tafiya kai tsaye zuwa ga burin da aka yi ba tare da haɗuwa da iskar gas ba. (Da bambanci, a cikin misalin tukunya mai tafasa, tururin ruwa yana tura iska daga tukunya kafin ya iya kaiwa ga murfin.) A matsin lamba na 10⁻⁴ Pa, ƙwayoyin 0.4-nm suna da matsakaicin hanyar kyauta na 60 m. Abubuwa masu zafi a cikin ɗakin evaporation, kamar su filaments masu zafi, suna samar da tururi da ba a so wanda ke iyakance ingancin iska.

Kwayoyin da suka haɗu da barbashi na kasashen waje na iya amsawa tare da su; alal misali, idan an ajiye aluminum a gaban iskar oxygen, zai samar da aluminum oxide. Har ila yau, suna rage yawan tururi da ya kai ga tushe, wanda ke sa kauri ya zama da wahala a sarrafa shi.

Abubuwan da aka kwashe sun ajiye ba daidai ba idan substratum yana da wani wuri mai laushi (kamar yadda aka haɗa da'irori sau da yawa). Saboda kayan da aka bushe sun kai farmaki ga substratum galibi daga hanya ɗaya, siffofi masu tasowa sun toshe kayan da aka fitar daga wasu yankuna. Wannan sabon abu ana kiransa "inuwa" ko "mataki".

Lokacin da aka yi evaporation a cikin mummunan iska ko kusa da matsin yanayi, sakamakon da aka samu ba daidai ba ne kuma ba ya zama fim mai ci gaba ko mai santsi. Maimakon haka, shaidar za ta bayyana a matsayin mai laushi.

Kayan aiki

Wani mai narkewa mai zafi tare da jirgin ruwa na molybdenum wanda aka gyara tsakanin manyan hanyoyin jan ƙarfe guda biyu da ruwa ya sanyaya.

Duk wani tsarin evaporation ya hada da famfo mai iska. Har ila yau, ya haɗa da tushen makamashi wanda ke fitar da kayan da za a ajiye. Akwai hanyoyin samar da makamashi daban-daban:

• A cikin hanyar zafi, ana ciyar da kayan ƙarfe (a cikin nau'in waya, pellets, harbi) a kan masu zafi (ceramic) da aka sani da "boats" saboda siffar su. Wani tafki na narkewar ƙarfe a cikin ramin jirgin ruwa kuma ya narke cikin girgije sama da tushen. A madadin haka ana sanya kayan tushe a cikin gicciye, wanda ke da zafi ta hanyar filament na lantarki, ko kuma ana iya rataye kayan tushe daga filament kanta (filament evaporation).
  • Molecular beam epitaxy wani nau'i ne na evaporation na zafi.
• A cikin hanyar lantarki, tushen yana dumama ta hanyar lantarki tare da makamashi har zuwa 15 keV.
• A cikin hasken iska, ana ciyar da waya mai kyau ko foda na kayan tushe a kai a kan yumbu mai zafi ko mashaya na ƙarfe, kuma yana narkewa a kan tuntuɓar.
• Ana aiwatar da evaporation mai tsayayya ta hanyar wucewa da babban halin yanzu ta hanyar waya mai tsayayye ko foil wanda ke dauke da kayan da za a ajiye. Sau da yawa ana kiran ɓangaren dumama a matsayin "maɓuɓɓugar narkewa". Ana yin maɓuɓɓugar evaporation na waya daga waya na tungsten kuma ana iya kafa su cikin filaments, kwando, masu dumama ko maɓuƙwalwar maɓuɓuɓɓuka. Ana yin nau'ikan nau'ikan jirgin ruwa daga tungsten, tantalum, molybdenum ko kayan aikin yumbu waɗanda zasu iya tsayayya da yanayin zafi.
• Induction dumama evaporation ya haɗa da dumama wani tushe kayan ta amfani da induction heater.

Wasu tsarin suna sanya substratum a kan wani Tsarin duniya na waje. Tsarin yana juyawa a lokaci guda a kusa da gatari biyu, don rage inuwa.

Ingantawa

• Tsabtacewar fim ɗin da aka ajiye ya dogara da ingancin iska, da kuma tsarkakar kayan tushe.
• A wani matsin lamba da aka ba shi tsarkakar fim din zai kasance mafi girma a mafi girman adadin ajiya kamar yadda wannan ya rage yawan dangi na shigar da ƙazantar gas.
• Kaurin fim din zai bambanta saboda yanayin ɗakin evaporation. Rashin jituwa tare da iskar gas yana ƙara rashin daidaituwa na kauri.
• Filament na waya don evaporation ba zai iya saka fina-finai masu kauri ba, saboda girman filament yana iyakance adadin kayan da za a iya ajiyewa. Jiragen ruwa da crucibles suna ba da girma mafi girma don murfin murfi. Rashin zafi yana ba da saurin ƙarancin ruwa fiye da sputtering. Flash evaporation da sauran hanyoyin da ke amfani da crucibles na iya sanya fina-finai masu kauri.
• Don saka wani abu, tsarin evaporation dole ne ya iya turɓaya shi. Wannan yana sa kayan da ba su da kyau kamar tungsten da wuya a saka ta hanyar hanyoyin da ba sa amfani da wutar lantarki.
• Rashin hasken lantarki yana ba da damar sarrafawa sosai na yawan evaporation. Don haka, tsarin lantarki mai haske tare da katako da yawa da kuma tushen da yawa na iya saka fili na sinadarai ko kayan haɗin da aka sani.
• Mataki na ɗaukar hoto

Aikace-aikacen

Injin narkewa da aka yi amfani da shi don yin amfani da ƙarfe a cibiyar fasaha ta LAAS a Toulouse, Faransa.

Wani muhimmin misali na tsarin evaporative shine samar da fim din kunshin fim na PET a cikin tsarin yanar gizo mai juyawa. Sau da yawa, Layer na aluminum a cikin wannan kayan ba shi da kauri don zama gaba ɗaya opaque tunda za'a iya ajiye wani nau'i mai kauri fiye da mai kauri. Babban manufar aluminum shine ware samfurin daga yanayin waje ta hanyar ƙirƙirar shingen ga wucewar haske, iskar oxygen, ko tururi na ruwa.

Kwatanta da sauran hanyoyin da za a iya saukewa

• Sauran hanyoyin da za a iya amfani da su don narkewa, kamar su sputtering da kuma sanya tururi na sinadarai, suna da mafi kyawun ɗaukar mataki. Wannan na iya zama fa'ida ko rashin fa'ida, dangane da sakamakon da ake so.
• Sputtering yana da alaƙa da saka kayan a hankali fiye da evaporation.
• Sputtering yana amfani da Plasma, wanda ke samar da ƙwayoyin halitta masu saurin gudu da yawa waɗanda ke bombarding substratum kuma suna iya lalata shi. Kwayoyin da aka narke suna da rarrabawar makamashi na Maxwellian, wanda aka ƙayyade ta zafin jiki na tushen, wanda ke rage yawan kwayar halitta masu saurin gudu. Koyaya, hasken lantarki yana samar da X-rays (Bremsstrahlung) da ɓarna electrons, kowannensu zai iya lalata substratum.

Manazarta

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• Na'urorin Semiconductor: Physics da Fasaha, na SM Sze, , yana da cikakken bayani game da sanya fim ta hanyar evaporation.ISBN 0-471-33372-7
• R. D. Mathis Company Evaporation Sources Catalog, by R. D, Company, shafuka 1 zuwa 7 da shafi na 12, 1992.