Kwii-diode ezikhupha ukukhanya (ii-LED) ezisekelwe kwi-GaN, inkqubela phambili eqhubekayo kwiindlela zokukhula kwe-epitaxial kunye noyilo lwezixhobo iqhubele phambili ukusebenza kakuhle kwe-quantum (IQE) kufutshane kakhulu neyona nto iphambili. Nangona le nkqubela phambili, ukusebenza okukhanyayo kwee-LED kuhlala kuncitshiswe ngokusisiseko kukusebenza kakuhle kokukhupha ukukhanya (i-LEE). Njengoko i-sapphire iqhubeka nokuba yinto ephambili kwi-epitaxy ye-GaN, i-surface morphology yayo idlala indima ebalulekileyo ekulawuleni ilahleko ze-optical ngaphakathi kwesixhobo.

Eli nqaku libonisa uthelekiso olubanzi phakathi kwe-flat sapphire substrates kunye ne-patternedii-substrates zesafire (PSS)Icacisa iindlela zokukhanya kunye ne-crystallographic apho i-PSS iphucula khona ukusebenza kakuhle kokukhupha ukukhanya kwaye ichaza isizathu sokuba i-PSS ibe ngumgangatho oqhelekileyo kwimveliso ye-LED esebenza kakhulu.

1. Ukusebenza kakuhle kokukhupha ukukhanya njengengxaki esisiseko

Ukusebenza kakuhle kwe-quantum yangaphandle (i-EQE) ye-LED kugqitywa yimveliso yezinto ezimbini eziphambili:

$EQE=IQE\times LEE\backslash text\{EQE\}\; =\; \backslash text\{IQE\}\; \backslash times\; \backslash text\{LEE\}$

EQE=IQE×LEE

Ngelixa i-IQE ilinganisa ukusebenza kakuhle kokuphinda kufumaneke imisebe ngaphakathi kwendawo esebenzayo, i-LEE ichaza iqhezu lee-photon ezivelisiweyo eziphuma ngempumelelo kwisixhobo.

Kwi-GaN-based LEDs ezikhuliswe kwi-sapphire substrates, i-LEE kwiindlela eziqhelekileyo zoyilo idla ngokulinganiselwa kwi-30–40%. Lo mda uvela ikakhulu kwi:

• Ukungafani okukhulu kwe-refractive index phakathi kweGaN (n ≈ 2.4), isafire (n ≈ 1.7), kunye nomoya (n ≈ 1.0)

• Ukubonakalisa okungaphakathi okuqinileyo (TIR) ​​kwiindawo zokujonga ezicwangcisiweyo

• Ukubanjwa kwe-photon ngaphakathi kweengqimba ze-epitaxial kunye ne-substrate

Ngenxa yoko, inxalenye enkulu yeefotoni eziveliswayo idlula kwiimbonakalo ezininzi zangaphakathi kwaye ekugqibeleni ifunxwa zizinto okanye iguqulwe ibe bubushushu endaweni yokuba inegalelo ekukhanyeni okuluncedo.

2. Ii-Flat Sapphire Substrates: Ubulula beSakhiwo kunye neMiqathango yokuBona

2.1 Iimpawu zoBume

Ii-sapphire substrates ezithe tyaba zihlala zisebenzisa i-c-plane (0001) orientation enomphezulu ogudileyo nocwangcisiweyo. Ziye zamkelwe ngokubanzi ngenxa yezi zinto zilandelayo:

• Umgangatho ophezulu wekristale

• Uzinzo oluhle kakhulu lobushushu kunye neekhemikhali

• Iinkqubo zokuvelisa ezivuthiweyo nezingabizi kakhulu

2.2 Indlela Yokusebenza Ngokubona

Ukusuka kwimbono yokukhanya, ii-planar interfaces zikhokelela kwiindlela zokusasazeka kwe-photon ezijolise kakhulu nezinokuqikelelwa. Xa ii-photon ezenziwe kwindawo esebenzayo ye-GaN zifikelela kwi-GaN–air okanye i-GaN–sapphire interface kwii-engile zesiganeko ezidlula i-engile ebalulekileyo, ukubonakaliswa kwangaphakathi okupheleleyo kwenzeka.

Oku kuphumela ekubeni:

• Ukuvalelwa kwe-photon okuqinileyo ngaphakathi kwesixhobo

• Ukufunxwa okwandisiweyo yi-electrodes zesinyithi kunye neemeko zeziphene

• Ukusasazwa okulinganiselweyo kwe-engile kokukhanya okukhutshiweyo

Enyanisweni, ii-substrates ze-sapphire ezisicaba azincedi kangako ekulweni nokuvalelwa kwamehlo.

3. Iisubstrates zeSapphire ezineePattern: Ingcamango kunye noYilo lweSakhiwo

I-substrate yesafire enepatheni (i-PSS) yenziwa ngokungenisa izakhiwo ze-micro- okanye ze-nanoscale ezihlala ixesha elide okanye ezihlala ixesha elide kumphezulu wesafire kusetyenziswa iindlela ze-photolithography kunye ne-etching.

Iijometri eziqhelekileyo zePSS ziquka:

• Izakhiwo zekhonikhi

• Iidome ezijikeleze i-Hemispherical

• Iimpawu zepiramidi

• Imilo ye-cylindrical okanye i-truncated-cone

Ubukhulu beempawu eziqhelekileyo buqala kwi-sub-micrometer ukuya kwi-micrometer ezininzi, ngobude obulawulwa ngononophelo, i-pitch, kunye nomjikelo womsebenzi.

4. Iindlela zokuphucula ukuKhutshwa kokukhanya kwiPSS

4.1 Ukucinywa koBuchule obupheleleyo bokuCamngca kwangaphakathi

I-topography ye-PSS enamacala amathathu iguqula ii-engile zendawo ze-incidence kwiindawo ezibonakalayo. Ii-photon ebezinokuba namava okubonakaliswa kwangaphakathi ngokupheleleyo kumda othe tyaba zithunyelwa kwii-engile ngaphakathi kwe-escape cone, nto leyo eyandisa kakhulu amathuba azo okuphuma kwisixhobo.

4.2 Ukusasazwa kwe-Optical okuphuculweyo kunye nokungacwangciswanga kwendlela

Izakhiwo ze-PSS zizisa iziganeko ezininzi zokurhawuzelelwa kunye nokucamngca, nto leyo ekhokelela koku:

• Ukungacwangciswanga kwemiyalelo yokusasazeka kwe-photon

• Ukwanda kokunxibelelana ne-interfaces zokukhupha ukukhanya

• Ixesha elincitshisiweyo lokuhlala kwi-photon ngaphakathi kwesixhobo

Ngokwezibalo, ezi ziphumo ziphucula amathuba okukhutshwa kwe-photon ngaphambi kokuba kufakwe.

4.3 Uvavanyo lwe-Refractive Index oluSebenzayo

Ukusuka kwimbono yokubonisa i-optical, i-PSS isebenza njengomaleko osebenzayo wokutshintsha i-refractive index. Endaweni yokutshintsha ngokukhawuleza i-refractive index ukusuka kwi-GaN ukuya emoyeni, ummandla onepateni ubonelela ngotshintsho oluqhubekayo lwe-refractive index, ngaloo ndlela kunciphisa ukulahleka kokubonakaliswa kweFresnel.

Le ndlela yokusebenza ifana ngokwengqiqo neengubo ezichasene nokukhanya, nangona ixhomekeke kwi-geometric optics endaweni yokuphazamiseka kwefilimu encinci.

4.4 Ukunciphisa Ngokungathanga Ngqo Ukulahlekelwa Yi-Optical Absorption

Ngokufinyeza ubude bendlela ye-photon kunye nokuthintela ukubonakaliswa kwangaphakathi okuphindaphindiweyo, i-PSS inciphisa amathuba okufunxwa kwe-optical ngoku:

• Izixhobo zokunxibelelana ngesinyithi

• Iimeko zeziphene zekristale

• Ukufunxwa kwe-Free-carrier kwi-GaN

Ezi ziphumo zinegalelo ekusebenzeni kakuhle okuphezulu kunye nokusebenza ngcono kobushushu.

5. Ezinye iingenelo: Ukuphuculwa koMgangatho weCrystal

Ngaphaya kokuphuculwa kwe-optical, i-PSS ikwaphucula umgangatho wezinto ze-epitaxial ngokusebenzisa iindlela ze-lateral epitaxial overgrowth (LEO):

• Ukususwa kweendawo okuvela kwi-interface ye-sapphire-GaN kuyaqondiswa kwakhona okanye kupheliswe

• Uxinano lokusasazeka kwemisonto luncitshiswe kakhulu

• Umgangatho ophuculweyo wekristale uphucula ukuthembeka kwesixhobo kunye nobomi bokusebenza

Le nzuzo imbini yokukhanya kunye nesakhiwo yahlula i-PSS kwiindlela zokulungisa ubuso ezikhanyayo kuphela.

6. Uthelekiso lobungakanani: I-Flat Sapphire vs. PSS

Impumelelo yokusebenza ixhomekeke kwijiyometri yepateni, ubude bomda wokukhupha, uyilo lweetshiphusi, kunye nesicwangciso sokupakisha.

7. Izinto eziqwalaselwayo malunga notshintshiselwano kunye nobunjineli

Nangona ineengenelo, i-PSS izisa imingeni emininzi esebenzayo:

• Amanyathelo ongezelelweyo e-lithography kunye nokugrumba anyusa iindleko zokwenza

• Ukufana kweepateni kunye nobunzulu be-etch kufuna ulawulo oluchanekileyo

• Iipateni eziphuculweyo kakuhle zinokuchaphazela kakubi ukufana kwe-epitaxial

Ke ngoko, ukulungiswa kwe-PSS ngumsebenzi obandakanya iinkalo ezininzi ezibandakanya ukulinganisa okubonakalayo, ubunjineli bokukhula kwe-epitaxial, kunye noyilo lwesixhobo.

8. Imbono yoShishino kunye neMbono yexesha elizayo

Kwimveliso ye-LED yanamhlanje, i-PSS ayisathathwa njengento yokuphucula ekhethwayo. Kwizicelo ze-LED ezinamandla aphakathi naphezulu—kuquka ukukhanyisa ngokubanzi, ukukhanyisa kweemoto, kunye nokukhanyisa i-backlights—ibe yiteknoloji esisiseko.

Iindlela zophando nophuhliso lwexesha elizayo ziquka:

• Uyilo oluphambili lwe-PSS olulungiselelwe usetyenziso lweMini-LED kunye neMicro-LED

• Iindlela ezidityanisiweyo zokudibanisa i-PSS kunye neekristale ze-photonic okanye i-nanoscale surface texturing

• Imizamo eqhubekayo yokunciphisa iindleko kunye neetekhnoloji zokulinganisa ezinokwandiswa

Isiphelo

Ii-substrates ze-sapphire ezineepateni zimele utshintsho olusisiseko ukusuka kwiinkxaso ze-mechanical ezingasebenziyo ukuya kwizixhobo ze-optical ezisebenzayo kunye nezolwakhiwo kwizixhobo ze-LED. Ngokujongana nokulahleka kokukhupha ukukhanya kwiingcambu zazo—oko kukuthi ukuvalelwa kwe-optical kunye nokubonakaliswa kwe-interface—i-PSS ivumela ukusebenza okuphezulu, ukuthembeka okuphuculweyo, kunye nokusebenza kwesixhobo okuzinzileyo.

Ngokwahlukileyo koko, nangona ii-sapphire substrates ezithe tyaba zihlala zintle ngenxa yokwenziwa kwazo kunye nexabiso eliphantsi, imida yazo yokukhanya ithintela ukufaneleka kwazo kwi-LEDs zesizukulwana esilandelayo ezisebenzayo. Njengoko itekhnoloji ye-LED iqhubeka nokutshintsha, i-PSS imi njengomzekelo ocacileyo wendlela ubunjineli bezinto ezinokuthi ziguqulele ngayo ngokuthe ngqo kwinzuzo yokusebenza kwinqanaba lenkqubo.