Low temperature near band edge recombination dynamics in ZnO nanorods

Abstract

Articles you may be interested inThe surface-plasmon-resonance and band bending effects on the photoluminescence enhancement of Agdecorated ZnO nanorods J. Appl. Phys. 116, 063108 (2014) The recombination dynamics of neutral donor bound excitons (D o X: I 4 , I 6/6a ) and near band edge defect-related emission in solution grown ZnO nanorods are investigated using steady state and time-resolved photoluminescence (PL) measurements. The effects of annealing are also studied. Low temperature steady state PL shows a systematic removal of the I 4 line after annealing at 450 C and the subsequent domination of I 6a in these PL spectra. Additionally, the time decay of the I 4 , I 6/6a, free exciton (FX), and basal plane stacking fault-related (BSF) PL transitions are studied as a function of annealing temperature. For the various annealing temperatures studied, the PL decay is described by a bi-exponential profile with a fast component (contribution from the surface) and slow component (related to bulk recombination). The fast component dominates in the case of as-grown and low temperature annealed samples (anneal temperatures up to 300 C), suggesting the presence of surface adsorbed impurities. For samples annealed above 400 C, the effects of the surface are reduced. The sample annealed at 850 C produced an overall enhancement of the crystal quality. The underlying mechanisms for the observed PL characteristics are discussed based on near surface band bending caused by surface impurities. V C 2014 AIP Publishing LLC.

Rapid synthesis of blue emitting ZnO nanoparticles for fluorescent applications

“…The most detail study of this transition was reported by Yalishev et al [12] and Wagner et al [3]. In their work, the 3.33 eV emission line was attributed to recombination of excitons bound to extended structural donor defect complexes which disappear at temperature of 10 K. Study done by Urgessa et al [26] on ZnO nanorods growth for temperature dependent PL also observe dominance of donor-bound exciton as possible reason for this emission. Fig.…”

“…Band edge emission centered at around 398.3 nm should be attributed to the recombination of excitons and V Zn [24,25]. However the origin of violet emissions centered at 3.07 eV(402.79 nm), 406.9 nm (3.04 eV) and 409.6 nm (3.02 eV) are ascribed to an electron transition from a shallow donor level of neutral Zn i to the top level of the valence band [26,27,9]. The broad deep level emission that started from UV to the visible region 360-480 nm with the maximum peak at 409.64 nm for the sample prepared at°200 C was observed.…”

Transport characteristics of n-ZnO/p-Si heterojunction as determined from temperature dependent current–voltage measurements

“…Additionally, the symmetry in the I-V curve (around 0 V) suggests that the nanorods are also heavily doped. It is also instructive to note that hydrogen, always present in these ZnO nanostructures, has been identified as a shallow donor and is most likely responsible for the large free carrier concentration at room temperature [13]. The I-V characteristics of heterojunction B, however, displays substantial rectification with a rectification ratio of 19 measured at 0.5 V ± .…”

Влияние Термических И Плазменных Обработок На Фотолюминесценцию Пленок Оксида Цинка

“…Немонотонное поведение интенсивности полосы NBE при термическом отжиге на воздухе с максимумом при ∼ 300−400 • С наблюдалось в ряде работ и объяснялось увеличением степени кристал-личности [11], десорбцией с поверхности гидроксильных групп [12] и примесных атомов, вызывающих безызлуча-тельную рекомбинацию [13].…”

“…Пред-полагается, что межузельный водород нестабилен при комнатной температуре и отжигается за несколько недель [28], а водород в позиции замещения стабилен до ∼ 500 • С [29,30]. В спектрах низкотемпературной ФЛ мелкому водородному донору, вводимому Н-обработкой, приписывают полосу I 4 [13,31,32] при ∼ 3.363 эВ, ко-торая идентифицирована как водород в кислородной вакансии (H O ) [33]. Водородному донору приписывают также линию при 3.360 эВ, идентифицированную как мелкий донор -водород в BC положении [33].…”