Mfundo yaikulu komanso momwe zinthu zilili panopa pa chipangizo chowunikira zithunzi cha avalanche (APD photodetector) Gawo Lachiwiri

Mfundo ndi momwe zinthu zilili panopachowunikira zithunzi cha chipale chofewa (Chowunikira zithunzi cha APDGawo Lachiwiri

2.2 Kapangidwe ka chip cha APD
Kapangidwe ka chip koyenera ndiye chitsimikizo chachikulu cha zipangizo zogwira ntchito bwino. Kapangidwe ka APD kamaganizira kwambiri nthawi ya RC yosasintha, kugwidwa kwa mabowo pa heterojunction, nthawi yodutsa yonyamula katundu kudzera m'dera lochepa ndi zina zotero. Kukula kwa kapangidwe kake kwafotokozedwa mwachidule pansipa:

(1) Kapangidwe koyambira
Kapangidwe ka APD kosavuta kwambiri kamachokera ku PIN photodiode, dera la P ndi dera la N ndi lodzaza kwambiri, ndipo dera loletsa kuphatikizika kawiri la N kapena P limayambitsidwa m'dera lapafupi la P kapena dera la N kuti lipange ma elekitironi achiwiri ndi ma hole pairs, kuti akwaniritse kukulitsa kwa primary photocurrent. Pazinthu za InP series, chifukwa hole impact ionization coefficient ndi yayikulu kuposa electron impact ionization coefficient, gain region ya N-type doping nthawi zambiri imayikidwa m'dera la P. Munthawi yabwino, mabowo okha ndi omwe amalowetsedwa m'dera la gain, kotero kapangidwe kameneka kamatchedwa hole-injected structure.

(2) Kuyamwa ndi kupindula zimasiyanitsidwa
Chifukwa cha mawonekedwe a InP okhala ndi band gap yayikulu (InP ndi 1.35eV ndipo InGaAs ndi 0.75eV), InP nthawi zambiri imagwiritsidwa ntchito ngati zinthu zopezera gain zone ndi InGaAs ngati zinthu zopezera absorption zone.

(3) Kapangidwe ka kuyamwa, kusinthasintha ndi kupindula (SAGM) kakuperekedwa motsatana
Pakadali pano, zida zambiri zamalonda za APD zimagwiritsa ntchito zinthu za InP/InGaAs, InGaAs ngati gawo loyamwa, InP pansi pa mphamvu yamagetsi yayikulu (>5x105V/cm) popanda kusweka, ingagwiritsidwe ntchito ngati zinthu zopezera gain zone. Pazinthu izi, kapangidwe ka APD iyi ndikuti njira yopulukira imapangidwa mu N-type InP chifukwa cha kugundana kwa mabowo. Poganizira kusiyana kwakukulu kwa band gap pakati pa InP ndi InGaAs, kusiyana kwa mphamvu ya pafupifupi 0.4eV mu valence band kumapangitsa mabowo opangidwa mu InGaAs absorption layer kutsekedwa pamphepete mwa heterojunction asanafike pa InP multiplier layer ndipo liwiro limachepa kwambiri, zomwe zimapangitsa kuti nthawi yayitali yoyankhira ndi bandwidth yopapatiza ya APD iyi. Vutoli likhoza kuthetsedwa powonjezera gawo losinthira la InGaAsP pakati pa zinthu ziwirizi.

(4) Kapangidwe ka kuyamwa, kusinthasintha, mphamvu ndi phindu (SAGCM) kaperekedwa motsatana
Pofuna kusintha kwambiri momwe magetsi amagawidwira pa gawo loyamwa ndi gawo loyamwa, gawo loyatsira limayikidwa mu kapangidwe ka chipangizocho, zomwe zimathandizira kwambiri liwiro la chipangizocho komanso momwe chimayankhira.

(5) Kapangidwe ka SAGCM kolimbikitsidwa ndi Resonator (RCE)
Mu kapangidwe kabwino kwambiri ka zozindikira zachikhalidwe zomwe tafotokozazi, tiyenera kuyang'ana mfundo yakuti makulidwe a gawo loyamwa ndi chinthu chotsutsana ndi liwiro la chipangizocho komanso mphamvu ya quantum. Kukhuthala kopyapyala kwa gawo loyamwa kumatha kuchepetsa nthawi yoyendera ya chonyamulira, kotero bandwidth yayikulu ingapezeke. Komabe, nthawi yomweyo, kuti mupeze mphamvu ya quantum, gawo loyamwa liyenera kukhala ndi makulidwe okwanira. Yankho la vutoli likhoza kukhala kapangidwe ka resonant cavity (RCE), ndiko kuti, Bragg Reflector (DBR) yogawidwa idapangidwa pansi ndi pamwamba pa chipangizocho. Galasi la DBR lili ndi mitundu iwiri ya zipangizo zomwe zili ndi index yotsika yoyamwa komanso index yokwera yoyamwa, ndipo ziwirizi zimakula motsatizana, ndipo makulidwe a gawo lililonse amakumana ndi kutalika kwa kuwala kwa incident light 1/4 mu semiconductor. Kapangidwe ka resonator ka chowunikira kakhoza kukwaniritsa zofunikira za liwiro, makulidwe a gawo loyamwa amatha kuchepetsedwa kwambiri, ndipo mphamvu ya quantum ya elekitironi imawonjezeka pambuyo pa kuwunikira kangapo.

(6) Kapangidwe ka mafunde olumikizidwa m'mphepete (WG-APD)
Njira ina yothetsera kutsutsana kwa zotsatira zosiyanasiyana za makulidwe a layer la absorption pa liwiro la chipangizo ndi efficiency ya quantum ndi kuyambitsa kapangidwe ka waveguide kogwirizana ndi m'mphepete. Kapangidwe kameneka kamalowa m'malo owunikira kuchokera kumbali, chifukwa layer la absorption ndi lalitali kwambiri, ndikosavuta kupeza efficiency yapamwamba ya quantum, ndipo nthawi yomweyo, layer la absorption lingapangidwe lochepa kwambiri, kuchepetsa nthawi yoyendera ya carrier. Chifukwa chake, kapangidwe kameneka kamathetsa kudalira kosiyana kwa bandwidth ndi efficiency pa makulidwe a layer la absorption, ndipo akuyembekezeka kukwaniritsa liwiro lapamwamba komanso lapamwamba la quantum efficiency. Njira ya WG-APD ndi yosavuta kuposa ya RCE APD, yomwe imachotsa njira yovuta yokonzekera galasi la DBR. Chifukwa chake, ndizotheka kwambiri m'munda wothandiza ndipo ndiyoyenera kulumikizana kwa common plane optical.

3. Mapeto
Kukula kwa chipale chofewachowunikira zithunziZipangizo ndi zipangizo zikuwunikidwanso. Kuchuluka kwa ma ionization a ma electron ndi mabowo a zinthu za InP kuli pafupi ndi kwa InAlAs, zomwe zimapangitsa kuti pakhale njira ziwiri zogwirira ntchito, zomwe zimapangitsa kuti nthawi yomanga chipale chofewa ikhale yayitali komanso phokoso liwonjezeke. Poyerekeza ndi zinthu za InAlAs zoyera, InGaAs (P) /InAlAs ndi In (Al) GaAs/InAlAs quantum well structures zili ndi chiŵerengero chowonjezeka cha ma coefficients a collision ionization, kotero magwiridwe antchito a phokoso amatha kusintha kwambiri. Ponena za kapangidwe kake, kapangidwe ka resonator enhanced (RCE) SAGCM structure ndi edge-coupled waveguide structure (WG-APD) zimapangidwa kuti zithetse kusagwirizana kwa zotsatira zosiyanasiyana za kuyamwa kwa layer thickness pa liwiro la chipangizo ndi mphamvu ya quantum. Chifukwa cha zovuta za njirayi, kugwiritsa ntchito kwathunthu kwa zinthu ziwirizi kuyenera kufufuzidwa kwambiri.