Simulaci da Bincike na Lasers na Bipolar Cascade na Tushen GaN tare da Ramin Quantum Wells mai Faɗin 25nm

Teburin Abubuwan Ciki

1. Gabatarwa & Bayyani

Wannan aikin yana gabatar da cikakkiyar simulaci da bincike na lambobi na sabon ƙirar Laser na Bipolar Cascade (BCL) na tushen GaN. Na'urar tana da tsari na musamman tare da yankuna masu aiki da yawa (ramukan quantum) waɗanda aka raba su da mahaɗan rami (TJs), wanda ke ba da damar sake yin amfani da electrons da ramuka don ingantaccen ingancin quantum wanda zai iya wuce 100%. Wani muhimmin siffa na musamman shine amfani da ramukan quantum na InGaN da ba a saba gani ba (25 nm), wanda ke ƙalubalantar ƙirar ƙira ta al'ada. Binciken yana amfani da tsarin lambobi masu daidaituwa da kai don warware kimiyyar lissafi na cikin na'ura, gano matsalolin aiki masu mahimmanci—wato sha na ciki, rashin ingantaccen gudanar da p-cladding, da dumama kai—da kuma ba da shawarar hanyoyin ingantawa. Wannan binciken yana da mahimmanci don ci gaba da lasers na semiconductor na nitride masu inganci, masu ƙarfi don aikace-aikace a cikin firikwensin, LiDAR, da tsarin masana'antu.

2. Tsarin Na'ura & Kimiyyar Lissafi

2.1 Ƙirar Layer na Epitaxial

Tsarin Laser, wanda aka yi cikakken bayani a cikin teburin da aka bayar, wani ingantaccen tari ne wanda aka girma ta hanyar plasma-assisted molecular beam epitaxy (PAMBE). Ya ƙunshi yankuna masu aiki guda biyu iri ɗaya na ramin quantum guda ɗaya (SQW) dangane da InGaN, waɗanda aka raba su kuma aka rufe su da mahaɗan rami na tushen InGaN. Mahaɗan ramin sun ƙunshi InGaN layers masu yawan doping n++ da p++ waɗanda aka ƙera don sauƙaƙe tunneling na tsakanin band. Yankin mai aiki yana cikin cikin layukan waveguide da cladding, tare da layukan toshewar electrons na AlGaN (EBLs) don ɗaukar masu ɗaukar kaya. Amfani da InGaN don duka yankuna masu aiki da TJ, sabanin GaN da aka fi sani da shi, wani muhimmin zaɓi ne na ƙira wanda ke tasiri daidaitawar band da filayen polarization.

2.2 Matsayin Faɗin Ramin Quantum Wells

Faɗin ramukan quantum na InGaN na 25 nm ya bambanta sosai da ramukan 2-4 nm na al'ada da ake amfani da su a cikin lasers na nitride. Simulacin ya nuna cewa waɗannan ramuka masu faɗi ba su ne tushen ribar gani ta farko daga matakan ƙasa ba. A maimakon haka, aikinsu na farko shine tara isasshen yawan masu ɗaukar kaya 'yanci a ƙananan matakan allura don rufe ƙaƙƙarfan filayen polarization da aka gina (piezoelectric da na kwatsam) waɗanda ke addabar tsarin heterostructures na nitride. Wannan rufewa yana daidaita tasirin Stark da aka keɓance na quantum (QCSE), yana rage rabuwar sararin samaniya na electrons da ramukan aikin wavefunctions kuma yana inganta ingancin sake haɗawa a kaikaice. Ana samar da ribar gani ta hanyar ƙarin ƙananan band ɗin makamashi a cikin waɗannan ramuka masu faɗi.

2.3 Tsarin Mahadar Rami

Mahaɗan ramin sune masu ba da damar aikin cascade. Suna ba da damar electrons waɗanda suka sake haɗuwa a wani yanki mai aiki don sake cika su ta hanyar tunneling daga band ɗin valence na layer p++ zuwa band ɗin conduction na layer n++, yana sake yin amfani da masu ɗaukar kaya yadda ya kamata don yanki mai aiki na gaba. Wannan sake yin amfani shine tushen samun ingantaccen ingancin quantum (DQE) sama da 100%, kamar yadda aka ruwaito a cikin abokin gwajin wannan na'urar da aka yi simulaci [7]. Ƙirar TJ dole ne ta daidaita ƙarancin juriya (yana buƙatar babban doping da shinge na bakin ciki) tare da bayyananniyar gani don rage asarar ciki.

3. Hanyar Simulaci & Muhimman Binciken

3.1 Tsarin Lambobi Mai Daidaituwa da Kai

Binciken ya dogara ne akan ingantaccen software na simulaci na lambobi, mai haɗa kimiyyar lissafi da yawa (misali, kama da kayan aikin kasuwanci kamar Crosslight ko Synopsys Sentaurus). Tsarin yana warware daidai da kai lissafin Poisson don lissafin lantarki, lissafin drift-diffusion don jigilar masu ɗaukar kaya, da kaddarorin kimiyyar lissafi na yankin mai aiki (misali, ta amfani da ka'idar k·p ko mai warware Schrödinger-Poisson). Wannan haɗin gwiwa yana da mahimmanci don ɗaukar daidai rikice-rikicen da ke tsakanin filayen polarization, rufewar masu ɗaukar kaya, igiyoyin tunneling, da ribar gani a cikin irin wannan tsari mara daidaituwa.

3.2 Iyakokin Aiki da aka Gano

Simulacin ya nuna manyan abubuwa uku da ke iyakance aikin Laser:

1. Sha na Ciki na Gani: Babban asarar sha yana faruwa a cikin yankunan p-type masu yawan doping, musamman a cikin mahadar rami da layukan p-cladding, yana rage ribar modal.
2. Ƙarancin Gudanar da p-Cladding: Ƙarancin motsi na rami da matsakaicin doping a cikin layer na p-AlGaN cladding yana haifar da babban juriya na jerin, yana haifar da dumama Joule mai yawa da allurar wutar lantarki mara daidaituwa.
3. Dumama Kai: Haɗin tasirin juriya na jerin da sake haɗuwa mara radiyo yana haifar da zafi mai mahimmanci, wanda ke ɗaga yanayin zafi na yankin mai aiki. Wannan yana rage ingancin quantum na ciki, yana ƙara ƙarfin kofa, kuma yana iya haifar da jujjuyawar zafi a manyan igiyoyi.

Waɗannan iyakokin suna kawar da fa'idodin da ake iya samu na sake yin amfani da masu ɗaukar kaya.

4. Sakamako & Tattaunawa

4.1 Rufe Masu ɗaukar Kaya a cikin Ramin Quantum Wells masu Faɗi

Sakamakon simulacin ya nuna a zahiri (misali, ta hanyar zane-zanen band) yadda yuwuwar lantarki a faɗin ramin quantum yake zama mai santsi yayin da yawan masu ɗaukar kaya ke ƙaruwa. A matakan allura na al'ada na Laser, filin polarization ya kusan cika rufe. Wannan tabbaci ne mai mahimmanci na hasashen ƙira. Bakan ribar da aka lissafa zai nuna cewa sauyin Laser na farko ba ya fitowa daga n=1 electron/rami sub-band, amma daga ƙarin sub-band (misali, n=2 ko n=3), waɗanda ke da mafi kyawun haɗin aikin wavefunctions saboda mafi yawan yuwuwar su ta tsakiya.

4.2 Tasirin Asarar Ciki

Cirewar lambobi na ribar modal daidai da yawan wutar lantarki (G-J) zai bayyana babban wutar lantarki mai bayyanawa da ƙarancin gangare fiye da yadda ake tsammani saboda sha na ciki. Halayen haske-wutar lantarki (L-I) da aka yi simulaci zai nuna babban ƙarfin kofa da ƙarancin ingancin gangare, daidai da ƙalubalen da ake fuskanta wajen tabbatar da haɓakar n-fold na gaske daga cascade na mahaɗan n. Tsarin yana ba da damar ƙididdige ma'aunin sha a cikin layukan p, wanda shine ma'auni mai mahimmanci don sake ƙira.

4.3 Tasirin Zafi & Dumama Kai

Module na simulaci na zafi, wanda aka haɗa shi da tsarin lantarki, zai haifar da bayanin yanayin zafi a cikin na'urar. Zai nuna wurare masu zafi kusa da ridge da cikin yankuna masu aiki. Binciken zai danganta wannan hawan zafi da jujjuyawar jan launi na tsawon lokacin watsawa da aka yi simulaci da lalata ingancin quantum na ciki da aka yi simulaci. Wannan yana nuna cewa sarrafa zafi ba abin damuwa na biyu bane amma babban ƙuntatawa ne na ƙira don lasers na cascade da ke nufin aiki mai ƙarfi.

5. Dabarun Ingantawa & Hanyoyin Gaba

Dangane da matsalolin da aka gano, simulacin ya ba da shawarar hanyoyin ingantawa da yawa:

• Injiniyan Cladding & Layer TJ: Maye gurbin layukan p-type masu sha da kayan bandgap mafi faɗi (misali, AlGaN mai ƙarar Al) ko bincika tsarin da aka yi doping polarization don inganta gudanarwa ba tare da ƙara sha ba. Inganta bayanan doping TJ da kauri don rage faɗuwar wutar lantarki da sha.
• Gudanar da Zafi: Aiwatar da raunin substrate, haɗin flip-chip, ko amfani da masu yada zafi na lu'u-lu'u don fitar da zafi yadda ya kamata daga yankin mai aiki.
• Ingantaccen Ƙirar Yankin Aiki: Yayin da ramukan quantum masu faɗi ke rufe filayen, ana iya ƙara ƙera kaddarorin ribar su. Bincika ramukan quantum masu haɗawa ko yankuna masu aiki na superlattice na iya ba da mafi kyawun sarrafa bakan riba da ingancin bambanci.
• Ƙaddamarwa zuwa Ƙarin Mahadar: Alkawari na ƙarshe na lasers na cascade yana cikin tara yankuna masu aiki da yawa. Aikin nan gaba dole ne ya magance tasirin tarawa na juriya na jerin, asarar gani, da samar da zafi a cikin tarin tare da mahaɗan 3, 5, ko fiye, mai yuwuwa don aikace-aikacen bugun jini mai ƙarfi a cikin LiDAR na mota.

Canji daga na'urorin bincike na PAMBE zuwa tsarin MOVPE masu yin kayan aiki ya kasance babban ƙalubale na kayan aiki, musamman game da kunna p-dopants a cikin TJs ba tare da matsalolin wucewa na hydrogen ba.

6. Ra'ayin Mai Bincike: Fahimtar Jiki & Abubuwan Da Ake Iya Aiwatarwa

Fahimtar Jiki: Wannan takarda tana ba da tabbataccen bincike na gaskiya. Manufar "faɗin ramin quantum + mahadar rami" cascade yana da hikima sosai don magance matsalolin polarization na nitride da ba da damar sake yin amfani da masu ɗaukar kaya, amma simulacin ya fallasa a zahiri cewa aikin na zahiri yana ƙarƙashin matsalolin injiniyan semiconductor na yau da kullun, amma masu mahimmanci: sha, juriya, da zafi. Ingantaccen ingancin quantum >100% wanda ke jawo hankalin kanun labarai wani lamari ne mai rauni, cikin sauƙi ana nutsar da shi da waɗannan tasirin parasitic.

Kwararar Ma'ana: Marubutan sun yi amfani da simulaci sosai azaman kayan aikin bincike. Sun fara da na'urar gwaji mai ban sha'awa [7], sun warware sabbin fasali (ramukan quantum masu faɗi, TJs), sannan suka gudanar da na'urar kama-da-wane tsarin zuwa gazawa. Ma'anar ba ita ce tabbatar da cewa manufar tana aiki daidai ba, amma gwada ta da ƙarfi da nemo maki karya. Wannan yana da ƙima sosai ga fagen fiye da binciken tabbatarwa mai sauƙi.

Ƙarfi & Kurakurai: Babban ƙarfi shine zurfin tsarin jiki. Ba ya ɗaukar TJ a matsayin mai juriya mai sauƙi ko faɗin ramin quantum tare da kaddarorin gawa. Haɗin kai da kai shine mabuɗi. Kurakuri, gama gari ga takardun simulaci da yawa, shine rashin kwatanta kai tsaye, na ƙididdiga tsakanin lanƙwan L-I da aka yi simulaci da waɗanda aka auna daga [7]. Nuna yadda tsarin ya yi hasashen ainihin ƙarfin kofa da gangare zai kasance tabbataccen tabbaci. Dogaro da "kyakkyawar yarjejeniya" ɗan gajeren hanya ne.

Fahimtar Aiki: Ga injiniyoyin na'ura, saƙon a bayyane yake: daina mayar da hankali kawai akan sihirin yankin mai aiki. Don buɗe yuwuwar lasers na cascade na nitride, ƙirar ƙira a layi daya a cikin yankuna marasa aiki ya zama dole. Taswirar hanya ya kamata ta ba da fifiko: 1) Haɓaka mafita na p-cladding masu ƙarancin asara, masu ingantaccen gudanarwa—watakila neman sabbin dabarun doping ko madadin kayan kamar InAlN lattice daidai da GaN. 2) Kula da ƙirar zafi a matsayin la'akari na ƙa'idar farko, ba abin da ake yi tunani bayan haka ba. 3) Amfani da wannan tsarin simulaci a matsayin dandalin gwaji na kama-da-wane don ƙirar ƙira da sauri da zaɓar ƙirar TJ da waveguide na gaba kafin farawar epitaxial mai tsada.

7. Ƙarin Bayani na Fasaha

7.1 Tsarin Lissafi

Jigon simulacin yana warware lissafin haɗe-haɗe. Ana siffanta jigilar masu ɗaukar kaya ta hanyar tsarin drift-diffusion: $$J_n = q \mu_n n \nabla \phi_n, \quad J_p = q \mu_p p \nabla \phi_p$$ inda $J_{n,p}$ suke yawan wutar lantarki, $\mu_{n,p}$ suke motsi, $n,p$ suke yawan masu ɗaukar kaya, kuma $\phi_{n,p}$ suke yuwuwar Fermi. Waɗannan an haɗa su da lissafin Poisson: $$\nabla \cdot (\epsilon \nabla \psi) = -q(p - n + N_D^+ - N_A^- + \rho_{pol})$$ inda $\psi$ shine yuwuwar lantarki, $\epsilon$ shine izinin, kuma $\rho_{pol}$ shine ƙayyadaddun yawan cajin polarization a mahaɗa, kalma mai mahimmanci ga nitrides. Ana ƙididdige ribar gani $g(E)$ daga tsarin lantarki, sau da yawa ta amfani da hanyar k·p don tantance makamashi na ƙananan band da ayyukan wavefunctions, sannan a kimanta abubuwan matrix na canji.

7.2 Misalin Tsarin Bincike

Nazarin Shari'a: Ƙididdige Matsalar Sha
Manufa: Ware gudummawar sha na layer p zuwa jimillar asarar ciki.
Hanya:

1. Daga bayanan simulaci na sararin samaniya na yanayin gani da yawan masu ɗaukar kaya 'yanci, lissafa ma'aunin sha na masu ɗaukar kaya 'yanci (FCA) a kowane layer: $\alpha_{fc} = C \cdot n^{\gamma}$, inda $C$ da $\gamma$ suke ma'auni masu dogaro da kayan (misali, daga S. Nakamura et al., J. Appl. Phys., 1996).
2. Lissafa haɗin haɗin modal $\Gamma_i$ tare da kowane layer mai asara i.
3. Gudummawar asarar modal daga layer i ita ce $\alpha_{i,modal} = \Gamma_i \cdot \alpha_{fc,i}$.
4. Ƙara gudummawar daga duk layukan p-type (p-cladding, layukan p-TJ, p-waveguide) don samun jimillar asarar modal na p $\alpha_{p,total}$.
5. Kwatanta $\alpha_{p,total}$ da asarar madubi $\alpha_m = (1/L) \ln(1/R)$ da sauran asarar. Idan $\alpha_{p,total}$ yayi daidai ko ya fi $\alpha_m$ girma, zai zama babban mai iyakance ingancin gangare.

Sakamako: Wannan binciken zai ba da manufa bayyananne, na ƙididdiga don inganta kayan aiki (misali, "Muna buƙatar rage FCA a cikin p-cladding da kashi 3").

8. Nassoshi

1. S. Nakamura, et al., "The Blue Laser Diode: The Complete Story," Springer, 2000. (Rubutu na tushe akan fasahar GaN)
2. R. F. Kazarinov da R. A. Suris, "Possibility of the amplification of electromagnetic waves in a semiconductor with a superlattice," Sov. Phys. Semicond., 1971. (Ka'idar farko akan tsarin cascade)
3. G. Muziol, et al., "Bipolar Cascade Lasers with 25-nm-Thick Quantum Wells," Appl. Phys. Express, 2019. (Takardar gwaji akan na'urar da aka yi simulaci)
4. J. Piprek, "Semiconductor Optoelectronic Devices: Introduction to Physics and Simulation," Academic Press, 2003. (Littafin karatu akan hanyoyin simulacin da aka yi amfani da su)
5. Isola, P., et al. "Image-to-Image Translation with Conditional Adversarial Networks." CVPR, 2017. (Takardar CycleGAN, wacce aka ambata a matsayin misali na ra'ayi mai canzawa amma mai ƙuntatawa a aikace, kama da manufar Laser cascade).
6. Ma'aikatar Makamashi ta Amurka. "Solid-State Lighting R&D Plan." 2022. (Yana nuna ci gaba da mayar da hankali kan raguwar inganci da ingantattun tsarin na'ura a cikin LEDs da lasers na nitride).