[PDF]    http://dx.doi.org/10.3952/physics.v55i4.3222

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 55, 264–273 (2015)
EXCITONIC LIGHT EMISSION DECAY TIME MEASUREMENTS IN MODERATELY δ-DOPED GaAs/AlAs MULTIPLE QUANTUM WELLS
Jurgis Kundrotasa, Aurimas Čerškusa, Gintaras Valušisa, Edmund Harold Linfieldb, Eric Johannessenc, and Agne Johannessenc
aSemiconductor Physics Institute of Center for Physical Sciences and Technology, A. Goštauto 11, LT-01108 Vilnius, Lithuania
E-mail: aurimas.cerskus@ftmc.lt
bSchool of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
cBuskerud and Vestfold University College, Raveien 215, 3184 Borre, Norway

 Received 23 June 2015; revised 10 August 2015; accepted 29 September 2015

The radiative recombination rate of moderately doped n-type and p-type GaAs/AlAs multiple quantum wells using a time-correlated single photon counting system is presented. The experimental study has been obtained within a wide temperature range from liquid helium to room temperature and the work has focused on identifying photoluminescence decay rates based on free-exciton recombinations. It was found that the free exciton decay time was reduced in doped multiple GaAs/AlAs quantum wells, and that the reduction rate depends on both the concentration and doping type.
Keywords: quantum well, photoluminescence, lifetime
PACS: 78.55.-m, 78.67.De, 78.47.jd

EKSITONINĖS SPINDULIUOTĖS GESIMO TRUKMIŲ MATAVIMAI VIDUTINIŠKAI δ-LEGIRUOTUOSE GaAs/AlAs KARTOTINIUOSE KVANTINIUOSE ŠULINIUOSE
Jurgis Kundrotasa, Aurimas Čerškusa, Gintaras Valušisa, Edmund Harold Linfieldb, Eric Johannessenc, Agne Johannessenc
aFizinių ir technologijos mokslų centro Puslaidininkių fizikos institutas, Vilnius, Lietuva
bLidso universitetas, Lidsas, Jungtinė Karalystė
cBuskerudo ir Vestfoldo universitetinis koledžas, Borre, Norvegija

Šiame darbe tirtos kartotinės kvantinės duobės buvo užaugintos molekulinių pluoštelių epitaksijos būdu ant didžiavaržių GaAs padėklų. Kvantinės GaAs 20 nm pločio duobės buvo atskirtos 5 nm pločio AlAs barjerais. Į kiekvienos kvantinės duobės vidurį buvo įterptas silicio (Si) donorinių arba berilio (Be) akceptorinių priemaišų δ sluoksnis.
Rekombinaciniai vyksmai buvo tirti plačiame temperatūrų intervale keičiant kvantinių duobių gardelės temperatūrą nuo 3,6 iki 300 K. Fotoliuminescencijos žadinimui naudojome diodu kaupinamą Nd:LSB kietojo kūno pikosekundinį lazerį. Dinaminiai fotoliuminescencijos vyksmai buvo tiriami naudojant koreliuotų pavienių fotonų skaičiavimo metodiką (TCSPC). Pagrindinis dėmesys skirtas laisvųjų eksitonų spinduliuotės gesimo trukmių tyrimui. Nustatyta, kad gesimo laikas sutrumpėja legiruotuose GaAs/AlAs kartotiniuose kvantiniuose šuliniuose. Jis priklauso nuo priemaišų tankio ir jų tipo: n ar p. Stipresnis gesimas stebimas n tipo bandiniuose esant mažesniems priemaišų tankiams. Prieita prie išvados, kad yra svarbūs kolektyviniai priemaišų reiškiniai, susiję su priemaišų banginių funkcijų persiklojimu ir Moto dielektrikas–metalas virsmu. n tipo priemaišoms būdinga mažesnė jonizacijos energija bei didesnis Boro radiusas lyginant su p tipo priemaišomis. Kolektyviniai reiškiniai pasireiškia n tipo kvantiniuose šuliniuose esant mažesniems tankiams.
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