Hole Trapping Centers Research Articles

The Effect of Be Co‐Doping on Luminescence Properties of Gd3Al3Ga2O12:Ce Glass Ceramics

The glass‐ceramics (GC) of gadolinium aluminum gallium garnets with the expected composition of Gd3Al3Ga2O12:Ce and Gd3Al3Ga2O12:Ce,Be (GAGG:Ce and GAGG:Ce,Be, respectively) are fabricated by crystallization from the Gd2O3–Al2O3–Ga2O3–CeO2–SiO2–BeO (Gd:Ga:Al ratio is close to 3:2:3) glasses. The influence of Be2+ co‐doping (including doping level) on the luminescent properties of the GAGG is demonstrated. In particular, Be co‐doping results in the suppression of the Ce3+‐related radioluminescence (RL) and as a consequence, the light yield is lowered as well. The conclusion is made that Be2+ creates effective electron or hole trapping centers.

Influence of GeO2 Content on the Spectral and Radiation-Resistant Properties of Yb/Al/Ge Co-Doped Silica Fiber Core Glasses.

In this study, Yb/Al/Ge co-doped silica fiber core glasses with different GeO2 contents (0–6.03 mol%) were prepared using the sol–gel method combined with high-temperature sintering. The absorption, fluorescence, radiation-induced absorption, continuous-wave electron paramagnetic resonance spectra, and fluorescence decay curves were recorded and analyzed systematically before and after X-ray irradiation. The effects of GeO2 content on the valence variations of Yb3+/Yb2+ ions, spectral properties of Yb3+ ions, and radiation resistance of Yb/Al/Ge co-doped silica glasses were systematically studied. The results show that even if the GeO2 content of the sample is relatively low (0.62 mol%), it can inhibit the generation of Yb2+ ions with slight improvement in the spectral properties of Yb3+ ions in the pristine samples and effectively improve its radiation resistance. Direct evidence confirms that the generation of trapped-electron centers (Yb2+/Si-E’/Al-E’) and trapped-hole centers (Al-OHC) was effectively inhibited by Ge co-doping. This study provides a theoretical reference for the development of high-performance, radiation-r esistant Yb-doped silica fibers.

Estimation of surface charge densities supporting seismo-electromagnetic phenomena through the surface charging mechanism

The mechanism of seismo-electromagnetic phenomena (SEP) related to electron and hole trapping centres in quartz has been discussed by estimating surface charge densities involved in the SEP. However, a few studies have estimated the densities from direct measurements of trapping centres in quartz produced by rock fracture and friction experiments. In this study, we estimated surface charge densities in quartz grains of simulated fault gouges produced by friction using electron spin resonance (ESR) for the gouges and a standard material with a known concentration of a trapping centre. We also estimated surface charge densities in fractured quartz grains from the previous data of the trapping centre concentrations obtained by ESR or a radical scavenger. The values in the fractured and sheared quartz were estimated as 6.51×10−6–6×10−1C/m2. These quantities are roughly enough to cause a corona discharge that can be a SEP source. Positive and negative charges are considered to be released from trapping centres and form electric dipoles generating electric and magnetic fields. Therefore, the trapping centres, especially the E1′ centre and the NBOHC, can be some of the main SEP sources. These values are divided into two groups depending on the amounts of the surface charge. The trapping centres decrease with time due to their chemical stability or chemical reactions with the air composition. Hence, we consider that the difference exists because the trapping centres are measured during, immediately after, or after a long period since fracture events. From this point of view, we propose two new SEP sources.

Hydrothermally grown ZnO:Mo nanorods exposed to X-ray: Luminescence and charge trapping phenomena

Peculiarities of the point defects creation under X-ray irradiation and the influence of Mo doping in ZnO powders ofnano- and microrods fabricated by the hydrothermal growth method (as-grown and annealed in air) were studied in detail. Correlated experiments of X-ray diffraction, X-ray photoelectron spectroscopy, electron paramagnetic resonance, photo- and radioluminescence as well as thermally stimulated luminescence allowed us to trace the effect of the molybdenum inclusion on the phase purity of synthesized materials and the role of Mo in the creation of X-ray induced point defects. Oxygen-based hole trapping centers (most probably involving interstitial oxygen) as well as Mo5+-based electron trapping centers were observed and their thermal stabilities were studied. Some amount of the hole trapping centers seemed to be directly connected with the creation of Mo5+. Zinc vacancies and the Mo5+ centers up to some extent were assumed to act as recombination centers for the holes released from the hole trapping centers. The X-ray irradiation also affects the luminescence properties of the ZnO:Mo samples – the intensity of the luminescence bands in general becomes weaker.

Unraveling electron liberation from Bi2+ for designing Bi3+-based afterglow phosphor for anti-counterfeiting and flexible X-ray imaging

It is challenging to rational design persistent luminescence and storage phosphors with high storage capacity of electrons and holes after X-ray charging. Such phosphors have potential applications in anti-counterfeiting and X-ray imaging. Here we have combined vacuum referred binding energy diagram (VRBE) construction, photoluminescence spectroscopy, and thermoluminescence to study the trapping processes of charge carriers in NaYGeO4. In NaYGeO4:0.004Bi3+ and NaYGeO4:0.004Bi3+,0.005Ln3+ (Ln = Tb or Pr), Bi3+ appears to act as a shallow electron trap, while Bi3+ and Ln3+ act as deep hole trapping and recombination centres. We will show how to experimentally determine the VRBE in the Bi2+ 2P1/2 ground state in NaYGeO4 and NaLuGeO4 by thermoluminescence study. The electron trap depth produced by Bi3+ codopant in NaLu1-xYxGeO4:0.003Bi3+,0.008 Tb3+ can be adjusted, by increasing x, resulting in conduction band engineering. By combining Bi3+ as an electron trap and Bi3+ and Tb3+ as the hole traps, excellent X-ray charged afterglow phosphors were developed. The integrated TL intensity of the optimized NaYGeO4:0.004Bi3+ and NaYGeO4:0.003Bi3+,0.008Tb3+ after exposure to X-rays is about 4.5 and 1.1 times higher than that of the state-of-the-art BaFBr(I):Eu2+ storage phosphor. Intense initial Tb3+ 4f → 4f afterglow appears in NaYGeO4:0.003Bi3+,0.008Tb3+ and more than 40 h afterglow is measurable in NaYGeO4:0.004Bi3+ and NaYGeO4:0.003Bi3+, 0.008 Tb3+ after X-ray charging. We will show proof-of-concept anti-counterfeiting and X-ray imaging applications by using the developed afterglow phosphors and CsPbI3 quantum dots. This work not only provides experimental evidence on the VRBE in the Bi2+ 2P1/2 ground state in NaYGeO4, but also shows how to design and develop good afterglow phosphors for anti-counterfeiting and X-ray imaging by deeply studying and controlling the trapping processes of charge carriers in bismuth and/or lanthanides doped inorganic compounds.

Charge trapping processes in hydrothermally grown Er-doped ZnO

Influence of X-ray irradiation on luminescence properties and defects creation was studied in the erbium doped hydrothermally grown ZnO by using the combination of photo- and radioluminescence (PL and RL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR). The photoluminescence properties of the ZnO:Er appeared affected by the X-ray irradiation – the intensity of the zinc vacancy-related red band and exciton-related ultraviolet band were weakened. The irradiation also evoked charge trapping and new centers creation whose type and number depended on Er doping. The X-ray induced defects were oxygen-based hole and electron trapping centers, O− and O2−, respectively. The X-ray irradiation had also influence on shallow donors in the bulk and at the surface of the ZnO nano- and microrods. TSL glow curves consisted of one broad peak with the maximum at about 110 K, its intensity was varying with the changing Er content. The glow peak was correlated with the thermal destruction of the unstable O2− electron trapping centers. Zinc vacancies-based defects participated in the thermally stimulated luminescence as recombination centers for the electrons released from the O2−.

Defects Induced Charge Trapping/Detrapping and Hysteresis Phenomenon in MoS2 Field-Effect Transistors: Mechanism Revealed by Anharmonic Marcus Charge Transfer Theory

One critical problem inhibiting the application of MoS2 field-effect transistors (FETs) is the hysteresis in their transfer characteristics, which is typically associated with charge trapping (CT) and charge detrapping (CDT) induced by atomic defects at the MoS2-dielectric interface. Here, we propose a novel atomistic framework to simulate electronic processes across the MoS2-SiO2 interface, demonstrating the distinct CT/CDT behavior of different types of atomic defects and further revealing the defect type(s) that most likely cause hysteresis. An anharmonic approximation of the classical Marcus theory is developed and combined with state-of-the-art density functional theory to calculate the gate bias-dependent CT/CDT rates. All the key electronic quantities are calculated with Heyd-Scuseria-Ernzerhof hybrid functionals. The results show that single Si-dangling bond defects are active electron trapping centers. Single O-dangling bond defects are active hole trapping centers, which are more likely to be responsible for the hysteresis phenomenon due to their significant CT rate and apparent threshold voltage shift. In contrast, double Si-dangling bond defects are not active trap centers. These findings provide fundamental physical insights for understanding the hysteresis behavior of MoS2 FETs and provide vital support for understanding and solving the reliability of nanoscale devices.

Effect of Li+ co-doping on the luminescence and defects creation processes in Gd3(Ga,Al)5O12:Ce scintillation crystals

Photo- and thermally stimulated luminescence characteristics, as well as photostimulated defects creation processes are investigated in the 85–510 K temperature range for the Li+ co-doped single crystal of Gd3(Ga,Al)5O12:Ce (GAGG:Ce). The results for GAGG:Ce,Li are compared with the corresponding characteristics of the GAGG:Ce and GAGG:Ce, Mg single crystals of similar host composition. The influence of Li+ and Mg2+ ions on the Ce3+ - related emission band position, temperature dependence of the photoluminescence intensity, efficiency of the Gd3+ → Ce3+ energy transfer, intensity and decay kinetics of the afterglow, and thermally stimulated luminescence characteristics is revealed. The presence of the Ce3+ → Ce4+ conversion in GAGG:Ce,Li is confirmed. The conclusion is made that, unlike GAGG:Ce,Mg, the compensation of the Li+ excess negative charge in GAGG:Ce,Li occurs due to both the Ce3+ → Ce4+ conversion and the effective formation of intrinsic crystal lattice defects. The origin of these defects as well as the origin of the electron and hole trapping centers in the GAGG:Ce,Li crystal are discussed.

Advanced reduction of bromate by UV/TiO2-Bi process without external sacrificial agents: Mechanism and applications

Recently, the heterogeneous advanced reduction processes (ARPs) for bromate (BrO3-) degradation have attracted considerable attention due to its stable performance and easy combination with UV disinfection. In this study, a UV/TiO2-Bi advanced reduction process (ARP) was established for BrO3- removal without adding external sacrificial agents. In the UV/TiO2-Bi ARP, Bi nanoparticles (NPs) doped on the TiO2 acted as hole trapping centers, while TiO2 NPs were used as reduction centers for the reduction of BrO3-, which enhanced the charge carrier separation. The UV/TiO2-Bi-1% ARP exhibited the highest BrO3- removal rate without the addition of sacrificial agents in the reaction solution compared to UV/TiO2 ARP and the UV/TiO2-Bi ARP at other Bi/Ti ratios. The result of 72% removal of 200 µg/L BrO3- at 60 min by 0.2 g/L TiO2-Bi-1% in tap water at pH 6.8 and 7.71 mg/L dissolved oxygen (DO) demonstrates the promising potential of the UV/TiO2-Bi ARP for the removal of BrO3- in practical applications. Compared to the 99.5% removal in deionized (DI) water at 60 min, lower BrO3- reduction in tap water was likely attributed to the consumption of photo-generated electrons by NO3– and the adsorption of natural organic matter on the surface of TiO2-Bi-1% nanocomposites. The study provides not only a novel BrO3- removal system with good photo-reduction performance, but also some guidance for the influence of constituents in raw water on the treatment of BrO3-.

High-resolution radiation detection using Ni/SiO2/n-4H-SiC vertical metal-oxide-semiconductor capacitor

In this article, we demonstrate the radiation detection performance of vertical metal-oxide-semiconductor (MOS) capacitors fabricated on 20 μm thick n-4H-SiC epitaxial layers with the highest energy resolution ever reported. The 100 nm SiO2 layer was achieved on the Si face of n-4H-SiC epilayers using dry oxidation in air. The Ni/SiO2/n-4H-SiC MOS detectors not only demonstrated an excellent energy resolution of 0.42% (ΔE/E×100) for 5.48 MeV alpha particles but also caused a lower enhancement in the electronic noise components of the spectrometer compared with that observed for the best high-resolution Schottky barrier detectors. The MOS detectors also exhibited a high charge collection efficiency (CCE) of 96% at the optimized operating bias despite the presence of the oxide layer. A drift-diffusion model applied to the CCE vs gate bias voltage data revealed a minority (hole) carrier diffusion length of 24 μm. Capacitance mode deep level transient spectroscopy (C-DLTS) scans in the temperature range 84–800 K were carried out to identify the resolution limiting electrically active defects. Interestingly, the C-DLTS spectra revealed both positive and negative peaks, indicating the simultaneous presence of electron (majority) and hole (minority) trap centers. It has been inferred that at the steady-state bias for the C-DLTS measurement, the MOS detector operates in the inversion mode at certain device temperatures, causing holes to populate the minority trap centers and, hence, manifests minority carrier peaks as well.

Electron and hole trapping in Li2MoO4 cryogenic scintillator

Abstract The origin and thermal stability of charge trapping centers were studied in Li2MoO4 cryogenic scintillators by correlated electron paramagnetic resonance (EPR) and thermally stimulated luminescence (TSL) measurements. Up to five electron and three hole trapping centers were detected in the crystals X-ray irradiated at 77 K. The electron traps were ascribed to MoO43− molecular complexes, unperturbed and perturbed by neighboring defects, while the hole traps – to O− lattice ions perturbed by lithium and molybdenum vacancies. The thermal stability of the trapping centers was studied and the depths of electron and hole traps were determined. The TSL peaks observed in the 77–300 K temperature range were related to the depletion of the detected paramagnetic centers. Influence of the revealed centers on the scintillation light yield is discussed.

Solution-Processed All-inorganic Planar Heterojunction Solar Cells by Employing In Situ Grown Interfacial Layer with Dual Functions: Complementary Absorption and Selective Extraction of Photogenerated Holes.

Photovoltaic conversion of renewable solar energy into electricity for sustainable energy production requires efficient, stable, and low-cost solar cells. Developing solution-processed all-inorganic solar cells is a practical scenario in virtue of the high charge mobility and good stability of inorganic semiconductors. Here, for the first time, we present a solution-processed all-inorganic planar heterojunction solar cell based on the nanoparticle film of copper indium sulfide (CuInS2) by using an antimony trisulfide (Sb2S3) nanoparticle film as an interfacial layer between the CuInS2 photon-harvesting layer and cathode. All of the component layers in the solar cell are in a superstrate architecture and sequentially in situ grown on a transparent conducting glass acting as anode by solution-processing methods. The dependences of device performance on the thickness of Sb2S3 film and the reduction of hole-trapping centers in the Sb2S3 film by thioacetamide treatment are investigated. The optimized all-inorganic device exhibits the best power conversion efficiency of 4.85% under AM 1.5G illumination and an excellent thermal stability. It is found that the Sb2S3 interfacial layer sandwiched between the CuInS2 photon-harvesting layer and counter-electrode has dual functions, that is, to provide complementary absorption after CuInS2 attenuation and to act as an effective hole-transporting layer to selectively extract photogenerated holes for effective charge collection efficiency.

Achieving high-performance multilayer MoSe2 photodetectors by defect engineering* *Project supported by the National Natural Science Foundation of China (Grant No. 61904043) and the Natural Science Foundation of Zhejiang Province, China (Grant No. LQ19A040009).

Optoelectronic properties of MoSe2 are modulated by controlled annealing in air. Characterizations by Raman spectroscopy and XPS demonstrate the introduction of oxygen defects. Considerable increase in electron and hole mobilities reveals the highly improved electron and hole transport. Furthermore, the photocurrent is enhanced by nearly four orders of magnitudes under 7 nW laser exposure after annealing. The remarkable enhancement in the photoresponse is attributed to an increase in hole trapping centers and a reduction in resistance. Furthermore, the annealed photodetector shows a fast time response on the order of 10 ms and responsivity of 3 × 104 A/W.

Identification of Channel Hot Carrier Stress-Induced Oxide Traps Leading to Random Telegraph Signals in pMOSFETs

We investigated the effect of channel hot carrier (CHC) stressing on the creation of gate oxide defect centers causing random telegraph signals (RTSs) in pMOSFETs. To identify these stress-induced hole traps in the oxide and fully characterize their trapping properties, variable temperature RTS measurements were performed from room temperature down to 215 K and repeated after each stressing interval, up to 1200 s. The trapping properties of the stress-induced defect sites and those present before stress are quantified, including the hole capture and emission activation energies, structural relaxation in the oxide network due to trapping/detrapping, and entropy change as well as the energy level and position of the trap in the oxide. Based on this information, disassociated III-Si and hydrogen bridge defects are identified as the hole trapping centers in SiO2. Difference was observed between the process- and stress-induced traps in the entropy change upon hole emission from the oxide trap to Si channel (electron capture from the Si valence band), implying the possibility of stress-induced structural defects being different than the native ones.

Insight into enhanced thermoluminescence property of (Mg, Cu, Ag)-Doped LiF:A DFT study

Thermoluminescence dosimeter (TLD) has been shown to be one of the most popular devices to measure absorbed radiation dose. Increasing applications of radiation in our day-to-day life motivates to develop efficient phosphor materials for TLD. LiF based TLD has attracted immense interest in the area of medical and industrial applications of radiation. Present study explored the origin of recent experimental observation of improvement of TL sensitivity of LiF due to doping with Mg, Cu and Ag. For this purpose, we have systematically investigated the geometry and electronic structure of LiF in absence and presence of individual dopant element as well as in combination using density functional theory as a tool. Present study indicates that the relative defect formation energy for doping with individual element and in combination is strongly dependent on the chemical environment. Our study reveals that the requirement of a good TLD material, i.e., electron trapping, hole trapping, and luminescent centers is not satisfied in presence of only individual dopant element. Interestingly, this condition is nicely fulfilled by simultaneous presence of all the three dopant elements. Each dopant element is found to play specific role in creating different types of trapping centers. Present study also explored the underlying mechanism of the TL process in (Mg, Cu, Ag)-doped LiF. To explain the origin of experimentally observed absorption and emission spectrum, we have calculated thermodynamic transition levels (TTLs), and optical transition levels for different doped systems. Finally, the present study predicts the emission range of (Mg, Cu, Ag)-doped LiF, which is known to be very much crucial for selecting the appropriate light detection system.

Role of Pr3+ ions as hole-trapping centers for the electroluminescence of (Ca0.6Sr0.4)0.998Pr0.002Ti0.9Al0.1O3−δ thin films

Thin-film electroluminescent devices composed of an (In0.975Sn0.025)2O3 anode, a phosphor, and a Sn0.95Sb0.05O2 cathode were prepared by a sol–gel and firing method. The phosphor thin films were composed of four layers, (Ca0.6Sr0.4)0.998Pr0.002Ti0.9Al0.1O3–δ or Ca0.6Sr0.4Ti0.9Al0.1O3–δ. The relation between the space distribution of Pr3+ ions and the electric/electroluminescence properties were investigated. The electroluminescence occurred predominantely at (Ca0.6Sr0.4)0.998Pr0.002Ti0.9Al0.1O3–δ layer closest to the anode. We suggested the electroluminescence mechanism that a hole injected from the anode is trapped at a Pr3+ ion, an electron injected from the cathode recombines with the trapped hole, and the Pr3+ ion is excited to emit a photon.

Study on intrinsic defects and copper doping in LiAlO2 crystal from combined first-principles and thermodynamic calculations

A large OSL (optically stimulated luminescence) response from copper replacing lithium (CuLi) in lithium aluminate (LiAlO2, LAO) has been reported in earlier studies, and the origin of the OSL response was isolated CuLi. However, other trapped-hole centers that are not involved in OSL response, such as CuLi–VLi and STH (self-trapped hole center, a hole localized at O ion adjacent to VLi), also appear in LiAlO2:Cu crystal after irradiation. To reach optimum OSL response of LAO crystal, a comprehensive analysis that integrates first-principles and thermodynamic calculations is employed to investigate the relative stability of intrinsic defects and Cu defects. Defect formation energies (DFE) of these defects are obtained from density functional theory (DFT), as well as corrected by finite-size corrections (FNV). To find the region of Fermi level where the crystal maintains electrical neutrality, we combine DFEs as a function of Fermi level for Cu defects and intrinsic defects to discuss the charge compensation mechanism. Then, the definite DFEs for these defects and the energetically preferred sites for substitutional Cu ions are shown after determining the locations of Fermi levels under different conditions. In O-rich conditions, the results show that CuAl is most stable with the decrease of the chemical potential of Al. Furthermore, CuLi is energetically preferred under O-poor conditions, and DFE of isolated CuLi is much lower than other Cu defects, thus, the optimum OSL signal occurs. To validate our conclusions, we also present the deformation charge density to study the chemical bonds of Li–O, Al–O, CuLi–O and CuAl–O. The results also suggest that it would cost more energy to destroy Al–O bond than Li–O bond.

Activation of multiple defects in zinc aluminate through gamma and UV irradiation

Versatile luminescence has always been the source of inspiration to explore the complex trap distribution in semiconducting oxides. In the continuation of reported investigation of effect of fuel type on the trap distribution and other properties of zinc aluminate (Jain et al., Sci. Rep. 10 (2020) 385), effect of fuel blends on defect structure is examined. A gradual transition from narrow to broad glow curves is observed on substituting urea fuel by monoethanolamine (MEA) during synthesis. In addition, type of irradiation (γ and UV radiation) is having a different impact on populating the traps and hence recombination kinetics. Deeper traps started contributing more with the increase in MEA fuel. Deconvolution of complex curves has enabled to visualize the presence of multiple traps with overlapping wavefunctions. Zn/Al vacancies act as hole trap centres and AlZn• antisite defect as an electron trap aided by neutral and charged oxygen vacancies (F and F+ centres) situated somewhat deeper in the forbidden gap. In order to provide a lucid understanding, phenomenon of trapping, de-trapping, re-trapping and recombination is depicted through a band model diagram. Presented study can be useful in tuning various properties of ZnAl2O4.

Structural, electronic and optical characterization of substitutional Ag defect in Li2B4O7 scintillator

The DFT based full-potential linear augmented plane-wave method has been employed to simulate computationally the Li2B4O7 scintillator with isolated Ag1+ impurity substituting for the Li1+ ion. With the objective to investigate the physics of the Ag1+ defect in pre- and post-irradiated compound, the unit cell of the Li2B4O7:Ag has been differently charged. It was found that additional electrons and holes were captured exactly by the Ag1+, confirming the experimental fact that this defect acts as an electron and a hole trapping center. It has been concluded that the Ag impurity can assume the Ag1+, Ag0, and Ag2+ charge states. The lattice position and the relaxed local structure around each of them have been determined and chemical bonding with neighboring atoms carefully analyzed. The Ag1+ defect is found to be dislocated from the Li site, while the Ag2+ is stabilized approximately at it, both being bonded only to neighboring oxygens. The Ag0 defect is dislocated from the Li site by approx. 1.0 Å and bonded to the oxygens and one boron ion, a fact which classifies it as an interstitial defect. Electronic structure and absorption coefficient spectra of the compound containing each of the 3 charged defects have been calculated. A comparison of the obtained results with experimental data shows that the 4d10 → 4d95s1 transitions at the sole Ag1+ defect are responsible for the optical response of the pre-irradiated compound (peak centered on 6.0 eV). The Ag2+ and Ag0 defects contribute to the additional absorption bands which appear after the X-ray irradiation of the compound. The absorption peak centered on 1.9 eV is due to 4d → 4d electronic transitions at the Ag2+ centers, while the Ag0 center contributes to the creation of the broad absorption band spread between 2.5 and 5.5 eV via the 5s → 5p and the 4d → 5s transitions. The present study interprets the results of the recent experimental studies and substantiates, in the largest part, their conclusions. Additionally, it predicts a shift of the 1.9 eV absorption peak to lower energies as a response to the light polarized along the crystalline c-axis.

RADIO-OPTICAL response of cerium-doped lithium gadolinium bismuth borate glasses

Bismuth borate glasses containing lithium and gadolinium were doped with (0.1–2.5 mol%) of Ce and their optical and radiation response were investigated. These modified glasses exhibited photoluminescent properties in response to the radiations, which were evidenced by their broad-band spectral features around 378 nm due to 5d→4f transitions of the Ce3+ ions. The intensity response of these glasses increased with increasing concentration of cerium up to 2.0 mol% which decreased upon further increase in the concentration of cerium due to the quenching effect and cross-relaxation between the nearest ions. Gamma irradiation of samples with 1 and 2 Gy doses demonstrated an increase in the intensity of photoluminescence peaks with increase in the irradiation dose. The observed increase caused the formation of relatively more electron and hole trap centers that eventually led to more recombinations in the glass matrix. This enhancement in the intensity after irradiation was also proportional to the dose as expected and the photoluminescence peaks observed for the irradiation samples were broader than those of un-irradiated samples. The observed decrease in intensity after irradiation of samples with high cerium concentration (i.e. 2.5 mol%) may be linked to the energy transfer and dissipation occurring during cross-relaxation among the nearest cerium ions.