Critical Thermodynamic Conditions for the Formation of p-Type β-Ga2O3 with Cu Doping

Zhang, Chuanyu; Li, Zhibing; Wang, Weiliang

doi:10.3390/ma14185161

Cited by 8 publications

(3 citation statements)

References 36 publications

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“…Previous studies have reported that Cu can introduce deep acceptor states near the valence band maximum of CuInSe 2 , as depicted in Figure 4. Density‐functional theory calculations have predicted two Cu‐related deep acceptor states, [ 59,60 ] which have also been observed through PL [ 61,62 ] and absorption measurements. [ 63 ] The defect transitions were found between 2.1 and 2.6 eV, which could be the defect close to the valence band of CuInSe 2 .…”

Section: Resultsmentioning

confidence: 97%

Shifting the Paradigm: A Functional Hole‐Selective Transport Layer for Chalcopyrite Solar Cells

Wang,

Song,

Gharabeiki

et al. 2024

Solar RRL

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Cu(In,Ga)Se2 solar cells with high efficiency rely on Ga grading to mitigate back surface recombination and achieve optimal performance. However, the inhomogeneous absorber has drawbacks, including increased non‐radiative loss and inadequate absorption. Therefore, a paradigm change has been demanded in the literatures, to passivate the back contact by introducing a hole selective transport layer. Here, we demonstrate a functional hole transport structure as an alternative to Ga grading. The novel hole transport structure is prepared as a double layer: co‐evaporated CuGaSe2, covered by In2O3, made by solution combustion synthesis. As demonstrated by micrographs, elemental mapping and photoluminescence spectroscopy, the oxide layer improves thermal stability and prevents Ga diffusion. However, during the absorber deposition process, a complete ion exchange of In and Ga takes place between the two layers. Incorporating this hole‐selective transport layer in co‐evaporated non‐graded CuInSe2 solar cells leads to significantly increased minority carrier lifetime, measured by time resolved photoluminescence from 5 ns to 113 ns, yielding an 80 meV improvement in quasi‐Fermi level splitting, as determined by absolute photoluminescence spectroscopy. The devices are finished with standard buffer/window layers and exhibit improved open circuit voltage, as well as a promising fill factor of over 71%, indicating good hole transport properties. These results experimentally demonstrate the passivation effect of the new hole transport layer as well as its good transport properties. Thus, high‐efficiency solar cells can be achieved without relying on Ga grading, enabled by a functional hole transport layer.This article is protected by copyright. All rights reserved.

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Section: Resultsmentioning

confidence: 97%

Shifting the Paradigm: A Functional Hole‐Selective Transport Layer for Chalcopyrite Solar Cells

Wang,

Song,

Gharabeiki

et al. 2024

Solar RRL

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“…However, achieving improved p-type conductivity in β-Ga 2 O 3 has been a persistent challenge. Thus, further research on appropriate acceptor doping is necessary [27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Further Characterization of the Polycrystalline p-Type β-Ga2O3 Films Grown through the Thermal Oxidation of GaN at 1000 to 1100 °C in a N2O Atmosphere

Wei,

Liu,

Shi

et al. 2023

Coatings

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The development of good-conductivity p-type β-Ga2O3 is crucial for the realization of its devices and applications. In this study, nitrogen-doped p-type β-Ga2O3 films with the characteristics of enhanced conductivity were fabricated through the thermal oxidation of GaN in a N2O atmosphere. To obtain insights into the underlying mechanism of the thermally activated transformation process, additional measurements of the oxidized films were performed at temperatures of 1000, 1050, and 1100 °C. Room-temperature photoluminescence (PL) spectra showed a moderate ultraviolet emission peak at 246 nm, confirming the generation of gallium oxide with a band gap of approximately 5.0 eV. The characteristics of polycrystalline and anisotropic growth were confirmed via normalized X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED) patterns. The amount of incorporated nitrogen was analyzed via secondary ion mass spectrometry (SIMS) to examine the effects of oxidation temperature. Furthermore, the ionization energy of the acceptor in the films oxidized at 1000, 1050, and 1100 °C was calculated and analyzed using temperature-dependent Hall test results. The results indicated that nitrogen doping played a significant role in determining p-type electrical properties. The activation energy of polycrystalline β-Ga2O3, prepared via the thermal oxidation of GaN in the N2O atmosphere, was estimated to be 147.175 kJ·mol−1 using an Arrhenius plot. This value was significantly lower than that obtained via both the dry and wet oxidation of GaN under O2 ambient conditions, thus confirming the higher efficiency of the thermal oxidation of GaN in a N2O atmosphere.

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“…p型. 2023年, Wang等 [11] 利用射频磁控溅射法在不同沉积温度下, 在蓝宝石衬底上制备了Zn掺杂 b-Ga 2 O 3 薄膜, 研究发现n掺杂b-Ga 2 O 3 薄膜为 p型, 但与未掺杂b-Ga 2 O 3 膜相比, Zn掺杂的b-Ga 2 O 3 膜的载流子浓度和迁移率都较低. 2021年, Zhang等 [12] 基于第一性原理和偶极子修正的理论计算得出, Cu掺杂b-Ga 卡片JCPDS 43-1012对比后 [13] , 而形成较高的光电流 [14] .…”

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Preparation and ultraviolet detection performance of Cu doped β-Ga2O3 thin films

Liu,

Feng,

et al. 2023

Acta Phys. Sin.

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A Solar-blind UV photodetectors (SBPs) have been attracting great attention due to their widely used in missile tracking, fire detection, biochemical analysis, astronomical observations, space-to-space communications, etc. At present, scholars are found that wide bandgap semiconductor materials such as AlxGa1-xN, Mg1Zn1-xO, diamond and β-Ga2O3are ideal semiconductor materials for developing high-performance SBPs. As the ultra-wide band gap semiconductor material, β-Ga2O3has the large band gap width of 4.9 eV, strong breakdown electric field, absorption edge located in the solar blind ultraviolet band (200-280 nm) and has high transmittance in the near ultraviolet and the whole visible band. Therefore, β-Ga2O3 is a very suitable material for making solar blind UV photodetectors. However, the p-type β-Ga2O3 is difficult to doping, which limits the further development of β-Ga2O3 devices. In this paper, the β-Ga2O3 thin films with different Cu doping contents were grown on sapphire substrates by chemical vapor deposition method, and the morphology, crystal structure and optical properties of β-Ga2O3 films were measured. The test results show that the surface of β-Ga2O3 films with different Cu contents is relatively smooth, and the (-201) diffraction peak positions shift to the lower degree side with increasing Cu content, which indicates that Cu2+ is substituted for Ga3+ into the β-Ga2O3 lattice. The optical absorption spectrum measurement indicated that the energy gaps of samples were evidently narrowed with increasing Cu doping concentration. Hall measurements results indicated that the Cu doped β-Ga2O3 thin films was p-type conductivity with a hole concentration of 7.36×1014, 4.83×1015 and 1.69×1016 cm−3, respectively. In addition, a photoconductive UV detector with MSM structure was prepared by evaporation of Au on a Cu-doped β-Ga2O3thin film, and its UV detection performance was studied. The results show that the photocurrent value of the devices increases with the increasing Cu contents. The Il/Id ratio is about 3.8×102 of 2.4% Cu content device under 254 nm light with at 10 V. The rise time and decay time of 0.11 s and 0.13 s, respectively. Furthermore, the responsivity and external quantum efficiency can reach up to 1.72 A/W and 841% under 254 nm light with a light intensity of 64 μW/cm2.

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Critical Thermodynamic Conditions for the Formation of p-Type β-Ga2O3 with Cu Doping

Cited by 8 publications

References 36 publications

Shifting the Paradigm: A Functional Hole‐Selective Transport Layer for Chalcopyrite Solar Cells

Shifting the Paradigm: A Functional Hole‐Selective Transport Layer for Chalcopyrite Solar Cells

Further Characterization of the Polycrystalline p-Type β-Ga2O3 Films Grown through the Thermal Oxidation of GaN at 1000 to 1100 °C in a N2O Atmosphere

Preparation and ultraviolet detection performance of Cu doped <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> thin films

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