Ultraviolet radiation-induced photovoltaic action in γ-CuI/β-Ga2O3 heterojunction

Ayhan, Muhammed Emre; Shinde, Mandar; Todankar, Bhagyashri; Desai, Pradeep; Ranade, Ajinkya K.; Tanemura, Masaki; Kalita, Golap

doi:10.1016/j.matlet.2019.127074

Cited by 27 publications

(15 citation statements)

References 24 publications

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“…It shows the shortest cut-off wavelength at around 270 nm, whereas conventional transparent conductive oxides (TCOs) belongs to the visible wavelength region. The applications for a monoclinic β-Ga 2 O 3 structure are such as in solar energy devices [ 16 ], passivation coating [ 17 ], optoelectronic devices [ 18 ], gas sensor [ 19 ], and deep ultraviolet radiation devices [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

First-Principles Studies for Electronic Structure and Optical Properties of Strontium Doped β-Ga2O3

et al. 2021

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The crystal structure, electron charge density, band structure, density of states, and optical properties of pure and strontium (Sr)-doped β-Ga2O3 were studied using the first-principles calculation based on the density functional theory (DFT) within the generalized-gradient approximation (GGA) with the Perdew–Burke–Ernzerhof (PBE). The reason for choosing strontium as a dopant is due to its p-type doping behavior, which is expected to boost the material’s electrical and optical properties and maximize the devices’ efficiency. The structural parameter for pure β-Ga2O3 crystal structure is in the monoclinic space group (C2/m), which shows good agreement with the previous studies from experimental work. Bandgap energy from both pure and Sr-doped β-Ga2O3 is lower than the experimental bandgap value due to the limitation of DFT, which will ignore the calculation of exchange-correlation potential. To counterbalance the current incompatibilities, the better way to complete the theoretical calculations is to refine the theoretical predictions using the scissor operator’s working principle, according to literature published in the past and present. Therefore, the scissor operator was used to overcome the limitation of DFT. The density of states (DOS) shows the hybridization state of Ga 3d, O 2p, and Sr 5s orbital. The bonding population analysis exhibits the bonding characteristics for both pure and Sr-doped β-Ga2O3. The calculated optical properties for the absorption coefficient in Sr doping causes red-shift of the absorption spectrum, thus, strengthening visible light absorption. The reflectivity, refractive index, dielectric function, and loss function were obtained to understand further this novel work on Sr-doped β-Ga2O3 from the first-principles calculation.

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Section: Introductionmentioning

confidence: 99%

First-Principles Studies for Electronic Structure and Optical Properties of Strontium Doped β-Ga2O3

et al. 2021

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“…γ-CuI with a bandgap of ~ 3.1 eV and p-type carrier mobility of ~ 40 cm 2 V −1 s −1 has been investigated for heterojunction devices with β-Ga 2 O 3 [17,18]. The lattice mismatch between the cubic phase γ-CuI (111) and β-Ga 2 O 3 along the c-axis is approximately 2%, indicating the possibility of fabricating a compatible heterostructure of γ-CuI (111) and β-Ga 2 O 3 for heterojunction device applications [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Temperature-dependent device properties of γ-CuI and β-Ga2O3 heterojunctions

et al. 2021

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Temperature-dependent studies of Ga2O3-based heterojunction devices are important in understanding its carrier transport mechanism, junction barrier potential, and stability at higher temperatures. In this study, we investigated the temperature-dependent device characteristics of the p-type γ-copper iodide (γ-CuI)/n-type β-gallium oxide (β‐Ga2O3) heterojunctions, thereby revealing their interface properties. The fabricated γ-CuI/β-Ga2O3 heterojunction showed excellent diode characteristics with a high rectification ratio and low reverse saturation current at 298 K in the presence of a large barrier height (0.632 eV). The temperature-dependent device characteristics were studied in the temperature range 273–473 K to investigate the heterojunction interface. With an increase in temperature, a gradual decrease in the ideality factor and an increase in the barrier height were observed, indicating barrier inhomogeneity at the heterojunction interface. Furthermore, the current–voltage measurement showed electrical hysteresis for the reverse saturation current, although it was not observed for the forward bias current. The presence of electrical hysteresis for the reverse saturation current and of the barrier inhomogeneity in the temperature-dependent characteristics indicates the presence of some level of interface states for the γ-CuI/β‐Ga2O3 heterojunction device. Thus, our study showed that the electrical hysteresis can be correlated with temperature-dependent electrical characteristics of the β‐Ga2O3-based heterojunction device, which signifies the presence of surface defects and interface states. Article Highlights We revealed the interface properties of p-type γ-copper iodide (γ-CuI) and n-type β-gallium oxide (β-Ga2O3) heterojunction. The developed heterostructure showed a large barrier height (0.632 eV) at the interface, which is stable at a temperature as high as 473 K. We confirmed the current transport mechanism at the interface of the heterojunction by analyzing the temperature dependent current–voltage characterization. Graphic abstract

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“…The main parameter that characterizes the one-way electrical transport of a diode is I F / I R . Most of the diode exhibit I F / I R larger than ≈7 × 10 5 except recent two devices with rather large interface areas as they focus on the increase of photocurrent in the pn diode [ 9 , 19 ]. The ideality factor η seems to be lower than 2 when the n -type materials are epi-films of ZnO or amorphous IGZO film while the η of the p -CuI/ n -SZTO is as large as 2.7–3.0, indicating that disorder effects in the CuI film can be further reduced by better annealing or growth conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Yet another promising application direction of the p -CuI/ n -SZTO diode is a self-powered UV photodetector [ 16 ]. Recently, the photo-response of various pn diode structures made of p -CuI films (or nanoparticles) and various n -type materials are widely being tested; those n -type materials include IGZO films [ 8 ], CsPbBr 3 crystals [ 9 ], ZnO:Au films [ 17 ], and ZnO films [ 18 ], and β-Ga 2 O 3 single crystals [ 19 ]. Once realized, those photodetectors made of the pn diode are expected to have self-powered characteristics and reliable responsivity under UV light illumination [ 8 , 9 , 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Electronic Band Alignment of a Transparent p-CuI/n-SiZnSnO Heterojunction Diode with a High Rectification Ratio

Lee

Kang

et al. 2021

Nanomaterials

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Transparent p-CuI/n-SiZnSnO (SZTO) heterojunction diodes are successfully fabricated by thermal evaporation of a (111) oriented p-CuI polycrystalline film on top of an amorphous n-SZTO film grown by the RF magnetron sputtering method. A nitrogen annealing process reduces ionized impurity scattering dominantly incurred by Cu vacancy and structural defects at the grain boundaries in the CuI film to result in improved diode performance; the current rectification ratio estimated at ±2 V is enhanced from ≈106 to ≈107. Various diode parameters, including ideality factor, reverse saturation current, offset current, series resistance, and parallel resistance, are estimated based on the Shockley diode equation. An energy band diagram exhibiting the type-II band alignment is proposed to explain the diode characteristics. The present p-CuI/n-SZTO diode can be a promising building block for constructing useful optoelectronic components such as a light-emitting diode and a UV photodetector.

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Ultraviolet radiation-induced photovoltaic action in γ-CuI/β-Ga2O3 heterojunction

Cited by 27 publications

References 24 publications

First-Principles Studies for Electronic Structure and Optical Properties of Strontium Doped β-Ga2O3

First-Principles Studies for Electronic Structure and Optical Properties of Strontium Doped β-Ga2O3

Temperature-dependent device properties of γ-CuI and β-Ga2O3 heterojunctions

Characteristics and Electronic Band Alignment of a Transparent p-CuI/n-SiZnSnO Heterojunction Diode with a High Rectification Ratio

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