Binciken Tsarin Zarra na Gibin Kore a cikin InGaN/GaN LEDs: Matsayin Bazuwar Gami na Indium

1. Gabatarwa & Matsalar Gibin Kore

III-nitride InGaN/GaN fitilun fitilun LED sune ginshiƙan hasken zamani na ƙarfafan jiki (SSL), tare da LED shuɗi suna cimma ingancin canjin wutar lantarki sama da 80%. Hanyar da ta fi yawa don samar da farin haske ta ƙunshi lulluɓe LED shuɗi da phosphor don rage ɗan fitowar haske zuwa rawaya/kore. Duk da haka, wannan asarar Stokes-shift tana iyakance inganci na ƙarshe. Mafi kyawun hanyar zuwa SSL mai inganci sosai shine haɗa launi kai tsaye ta amfani da LED semiconductor ja, kore, da shuɗi (RGB), wanda ke ba da damar inganci mafi girma da sarrafa haske.

Babban cikas ga wannan hanyar shine "gibin kore": raguwar inganci mai tsanani da tsari a cikin ingancin ƙwayoyin ciki (IQE) na LED masu fitar da haske a yankin kore-zuwa-rawaya (~530-590 nm) idan aka kwatanta da masu fitar da shuɗi da ja. Wannan aikin ya nuna cewa babban abin da ba a bincika sosai ba a cikin wannan gibin a cikin c-plane InGaN/GaN rijiyoyin ƙwayoyin (QWs) shine bazuwar asali na atom ɗin Indium a cikin gami na In_xGa_1-xN, wanda ya zama mafi cutarwa a yawan Indium da ake buƙata don fitar da hasken kore.

2. Hanyar Bincike: Simintin Tsarin Zarra Mai Karfi (Atomistic Tight-Binding Simulation)

Don bincika kaddarorin lantarki na nanoscale bayan samfuran ci gaba, binciken ya yi amfani da tsarin simintin atomatik mai karfi. Wannan hanyar tana lissafin tsarin atomatik na musamman da mahallin sinadarai na gida na kowane atom.

2.1. Tsarin Simintin

An lissafa tsarin lantarki ta amfani da samfurin sp³d⁵s* mai karfi tare da haɗin spin-orbit. An haɗa tasirin matsi daga rashin daidaituwar lattice tsakanin InGaN da GaN ta hanyoyin filin ƙarfi (VFF). An warware ma'auni na Schrödinger na guda ɗaya don tsarin QW don samun tsarin tsinkaya na electron da rami.

2.2. Ƙirƙirar Bazuwar Gami na Indium

An ƙirƙiri gami na InGaN a matsayin rarraba bazuwar atom ɗin Indium da Gallium akan sublattice cation bisa ga abun da aka sani x. An samar da yawancin fahimtar ƙididdiga (saituna) na gami kuma an yi simintin su don ɗaukar matsakaicin tarin kaddarori kamar abin matrix na gani, wanda ke sarrafa ƙimar haɗuwar haske.

3. Sakamako & Bincike

Simintin atomatik ya bayyana tasiri biyu masu haɗin kai da bazuwar gami ke motsa su.

3.1. Tasiri akan Haɗuwar Tsarin Tsinkaya (Wavefunction Overlap)

Ƙungiyoyin Indium na bazuwar suna haifar da mafi ƙanƙanta na ƙarfin gida wanda ke ƙayyade tsarin tsinkaya na rami sosai. Electron, ba su da tasiri sosai, sun kasance mafi yawan rarrabuwa. Wannan rabuwar sarari fiye da wanda tasirin quantum-confined Stark (QCSE) ya haifar yana ƙara rage haɗuwar tsarin tsinkaya na electron-rami, wanda shine shigar kai tsaye cikin ƙimar haske.

3.2. Ma'aunin Haɗuwar Haske (Radiative Recombination Coefficient) ($B$)

Ma'aunin haɗuwar haske na asali $B$ yana daidai da murabba'in abin matrix na motsi $|M|^2$, wanda kansa ya dogara da haɗuwar tsarin tsinkaya. Simintin ya nuna cewa $B$ yana raguwa sosai tare da ƙara abun da ke cikin Indium x. An dangana wannan raguwa ga ƙayyadaddun wuri da rikicewar gami ya haifar, yana ba da dalili na asali na kayan aiki don ƙarancin inganci a cikin QWs masu fitar da hasken kore, tun kafin a yi la'akari da lahani marasa haske.

4. Tattaunawa: Bayan QCSE

Duk da yake QCSE saboda filayen polarization a cikin QWs na c-plane sanannen mai iyakance inganci ne, wannan aikin ya nuna cewa rikicewar gami wani abu ne mai zaman kansa kuma mai haɗawa. A babban abun da ke cikin Indium, haɗin tasirin QCSE mai ƙarfi (jawo electron da rami) da ƙayyadaddun rami mai ƙarfi (manne rami zuwa ƙungiyoyin Indium masu yawa) ya haifar da "bugu biyu" wanda ke rage ingancin haske sosai. Wannan ya bayyana dalilin da yasa ƙara abun da ke cikin Indium kawai don isa tsayin raƙuman kore ke haifar da aikin mara kyau.

5. Fahimtar Jiki & Ra'ayi na Mai Bincike

Fahimtar Jiki: Neman masana'antu don haɗa gibin kore ya fi mayar da hankali kan rage lahani na macroscopic da filayen polarization. Wannan takarda tana ba da gyara mai mahimmanci, na nano-scale: bazuwar gami na InGaN da kansa shine mai kashe inganci na asali, na ciki a tsayin raƙuman kore. Ba kawai matsala ta "samfurin mara kyau" ba ne; matsala ce ta kimiyyar kayan aiki.

Kwararar Hankali: Hujja tana da kyau kuma tana jan hankali. 1) Fitar da kore yana buƙatar babban abun da ke cikin In. 2) Babban abun da ke cikin In yana ƙara bazuwar abun da ke ciki. 3) Bazuwar yana haifar da sauye-sauyen ƙarfin gida. 4) Waɗannan sauye-sauyen suna kama rami da fifiko, suna raba su da electron. 5) Wannan rabuwar yana rage ma'aunin haske $B$ kai tsaye. Silar daga tsarin atomatik zuwa aikin na'urar an kafa ta sarai ta hanyar gwajin lissafi.

Ƙarfi & Kurakurai: Ƙarfin yana cikin amfani da simintin atomatik mai zurfi don bayyana tsarin da ba a iya gani ga samfuran drift-diffusion na al'ada ko ci gaba, kamar yadda CycleGAN ta amfani da asarar daidaitaccen zagayowar ta bayyana sabbin yuwuwar a cikin fassarar hoto mara haɗin kai. Babban aibi, wanda marubutan suka yarda da shi, shine mayar da hankali kawai akan ma'aunin haske $B$. Ya kaucewa babbar matsala ta yadda sauye-sauyen gami na iya ƙara haɗuwar mara haske (misali, ta hanyar haɓaka ƙimar Shockley-Read-Hall kusa da ƙungiyoyin In), wanda wataƙila abokin haɗin gwiwa ne a cikin gibin kore. Cikakken samfuri dole ne ya haɗa tashoshi biyu na haske da mara haske, kamar yadda aka jaddada a cikin bita daga ƙungiyoyin bincike kamar shirin SSL na DOE.

Fahimtar Aiki: Wannan ba kawai aikin ilimi ba ne. Yana canza dabarun R&D. Na farko, yana ƙarfafa hujjar ƙaura daga c-plane zuwa substrates na GaN na rabin-polar ko marasa polar don kawar da QCSE, ta haka ne a cire babban maɓalli ɗaya kuma a ware matsalar gami. Na biyu, yana kira ga injiniyan kayan aiki da nufin rage rikicewar gami. Wannan na iya haɗawa da bincika dabarun girma don ƙarin haɗin In mai daidaituwa, amfani da gami na dijital (gajeren lokaci na InN/GaN superlattices maimakon gami na bazuwar), ko ma haɓaka sabbin mahadi na nitride tare da ƙunƙuntaccen bandgaps na ciki, rage buƙatar babban rabo na In. Hanyar gaba ba kawai "girma shi da kyau" ba ne, amma "ƙirƙira gami daban."

6. Cikakkun Bayanai na Fasaha & Tsarin Lissafi

Ƙimar haɗuwar haske $R_{rad}$ don semiconductor mai kai tsaye bandgap ana bayar da ita ta: $$R_{rad} = B \, n \, p$$ inda $n$ da $p$ suke yawan electron da rami, kuma $B$ shine ma'aunin haɗuwar haske. A cikin rijiyar ƙwayoyin, $B$ an samo shi daga Dokar Zinariya ta Fermi: $$B \propto |M|^2 \, \rho_{r}$$ Anan, $|M|^2$ shine murabba'in abin matrix na motsi, wanda aka matsaka akan duk jihohin da suka dace, kuma $\rho_{r}$ shine rage yawan jihohin. Lissafin atomatik ya mai da hankali kan $|M|^2$, wanda don canjin gani shine: $$|M|^2 = \left| \langle \psi_c | \mathbf{p} | \psi_v \rangle \right|^2$$ inda $\psi_c$ da $\psi_v$ suke tsarin tsinkaya na electron da rami, kuma $\mathbf{p}$ shine ma'aikacin motsi. Babban binciken shine cewa sauye-sauyen gami suna sa $\psi_v$ ya zama mai ƙayyadaddun wuri sosai, yana rage haɗin sarari a cikin lissafin abin matrix don haka yana rage $|M|^2$ kuma a ƙarshe $B$.

7. Mahallin Gwaji & Fassarar Taswira

Takardar tana nufin Hoto na ra'ayi na 1 (ba a sake yin shi a cikin guntun rubutu ba) wanda zai zama al'ada ya zana Ingancin Ƙwayoyin Waje (EQE) ko IQE akan tsayin raƙuman fitarwa don III-nitride (shuɗi-kore) da III-phosphide (ja) LEDs. Taswirar za ta nuna ƙwararren rami a yankin kore-rawaya—"gibin kore." Sakamakon simintin a cikin wannan takarda yana ba da bayanin microscopic ga gefen hagu (nitride) na wannan rami. Ragewar $B$ da aka annabta tare da ƙara abun da ke cikin In zai bayyana a gwaji a matsayin ƙarancin kololuwar IQE don LED tare da tsayin raƙuman manufa, ko da yawan lahani na kayan an riƙe shi akai-akai.

8. Tsarin Bincike: Nazarin Matsayi na Ra'ayi

Matsayi: Masana'antar LED ta lura da raguwar IQE da aka auna na 40% lokacin da aka canza kololuwar fitarwa na QW daga 450 nm (shuɗi) zuwa 530 nm (kore), duk da yin amfani da girke-girke iri ɗaya na girma waɗanda aka inganta don ƙarancin lahani na macroscopic.

Aikace-aikacen Tsarin:

1. Haɓaka Hasashe: Shin raguwar ta samo asali ne daga (a) ƙara lahani na maki, (b) ƙarfin QCSE, ko (c) kimiyyar gami ta ciki?
2. Warewar Lissafi: Yi amfani da samfurin atomatik mai karfi kamar yadda aka bayyana. Shigarwa: abun da aka sani na In don QWs shuɗi da kore. Riƙe duk sauran sigogi (faɗin rijiya, abun da ke cikin shinge, matsi) akai-akai a cikin samfurin.
3. Simintin Sarrafawa:
   • Gudu 1: Yi simintin tare da cikakken tsari (ƙirar ƙirar kwayoyin halitta) na gami na InGaN. Lura da canjin haɗuwar tsarin tsinkaya da $B$ saboda ƙara filin polarization (QCSE) kawai.
   • Gudu 2: Yi simintin tare da gami na bazuwar na gaske don duka abun da ke ciki. Lura da ƙarin raguwar $B$.
4. Bincike: Ƙididdige yawan gudunmawar QCSE mai tsafta da rikicewar gami ga jimlar raguwar $B$. Wannan yana raba tasirin biyu.
5. Sakamako Mai Aiki: Idan rikicewar gami ya ba da gudunmawar >50% na raguwar $B$, dabarun haɓakawa yakamata su juya zuwa ga injiniyan gami (misali, bincika gami na dijital) maimakon neman ƙarin rage lahani ko sarrafa polarization kawai.

9. Aikace-aikace na Gaba & Hanyoyin Bincike

• Haɓaka LED Marasa Polar da Rabin Polar: Kawar da QCSE a cikin GaN marasa polar/rabin polar zai bayyana tasirin tsafta na sauye-sauyen gami, yana tabbatar da wannan samfurin da kuma saita sabon tushen inganci don masu fitar da kore.
• Injiniyan Gami: Bincike cikin dabarun girma (misali, MOCVD mai bugun jini, gyaran rabo na V/III) don cimma ƙarin haɗin In mai daidaituwa. Binciken "gami na dijital" (gajeren lokaci na InN/GaN superlattices) a matsayin maye gurbin InGaN na bazuwar, yana ba da abun da ke ciki da sarrafawa da yuwuwar rage ƙayyadaddun wuri.
• Sabbin Tsarin Kayan Aiki: Binciken madadin mahadi na nitride (misali, GaNAs, babban abun da ke cikin InAlN) ko kayan aiki na 2D waɗanda zasu iya cimma fitar da kore ba tare da babban rabo na gami na bazuwar ba.
• Gine-ginen Na'ura Mai Ci Gaba: Ƙirƙirar QWs tare da bayyanannun bayyanannun ƙarfi (misali, abun da aka ƙayyade, yadudduka delta) don magance tasirin ƙayyadaddun rami na ƙungiyoyin In.
• Haɗin Ƙirar Ƙirar Ma'auni Daban-daban: Haɗa sakamakon atomatik da aka gabatar anan tare da manyan samfuran drift-diffusion ko Monte Carlo na motsi don annabta cikakkun halayen na'urar LED a ƙarƙashin yanayin aiki.

10. Nassoshi

1. S. Nakamura, T. Mukai, M. Senoh, "Candela-class high-brightness InGaN/AlGaN double-heterostructure blue-light-emitting diodes," Appl. Phys. Lett., vol. 64, no. 13, pp. 1687–1689, 1994. (Cikakken nasara na 1993 da aka ambata).
2. M. R. Krames et al., "Status and Future of High-Power Light-Emitting Diodes for Solid-State Lighting," J. Disp. Technol., vol. 3, no. 2, pp. 160–175, 2007. (Ambaton inganci >80%).
3. Ma'aikatar Makamashi ta Amurka, "Solid-State Lighting R&D Plan," 2022. (Tushe mai iko akan yuwuwar SSL da haɗa launi).
4. J. Y. Tsao et al., "Toward smart and ultra-efficient solid-state lighting," Adv. Opt. Mater., vol. 2, no. 9, pp. 809–836, 2014.
5. E. F. Schubert, Light-Emitting Diodes, bugu na 3. Cambridge University Press, 2018. (Tushen daidaitaccen bayani akan kimiyyar LED, gami da gibin kore).
6. Z. Zhuang, D. Iida, K. Ohkawa, "Review of long-wavelength III-nitride semiconductors and their applications," J. Phys. D: Appl. Phys., vol. 54, no. 38, p. 383001, 2021. (Bita na kwanan nan wanda ya rufe gibin kore).
7. J. Jun et al., "The potential of III-nitride laser diodes for solid-state lighting," Prog. Quantum Electron., vol. 55, pp. 1–31, 2017.
8. C. J. Humphreys, "The 2018 nitride semiconductor roadmap," J. Phys. D: Appl. Phys., vol. 51, no. 16, p. 163001, 2018. (Yana tattauna QCSE da ƙalubalen kayan aiki).
9. P. G. Eliseev, P. Perlin, J. Lee, M. Osinski, "'Blue' temperature-induced shift and band-tail emission in InGaN-based light sources," Appl. Phys. Lett., vol. 71, no. 5, pp. 569–571, 1997. (Aikin farko akan tasirin ƙayyadaddun wuri).
10. J. Zhu, T. Shih, D. Yoo, "Atomistic simulations of alloy fluctuations in InGaN quantum wells," Phys. Status Solidi B, vol. 257, no. 6, p. 1900648, 2020. (Aikin zamani mai alaƙa).