Quasi‐Single Crystalline Cuprous Oxide Wafers via Stress‐Assisted Thermal Oxidation for Optoelectronic Devices

Abstract

P-type semiconductor cuprous oxide (Cu 2 O) offers promising optoelectronic applications such as solar cells and photodetectors owing to its considerable absorption coefficients and high carrier mobility. However, polycrystalline Cu 2 O films with low carrier mobility resulting from excessive grain boundaries and structure disorder fail to meet the demands for these optoelectronic applications. Here a stress-assisted thermal oxidation method to fabricate p-type <110>-textured quasi-single crystalline Cu 2 O (c-Cu 2 O) wafers with centimeter-scale grains is developed. It is found that strain energy induced by thermal contact stress plays a critical role in crystal growth. The resultant <110>-textured quasi-single c-Cu 2 O wafers exhibit excellent crystallinity with rocking curve having a low full width at half maximum of 0.022°, a low defect density of 2 × 10 11 cm −3 , a high mobility exceeding 100 cm 2 V −1 s −1 , and a long minority lifetime of 98.5 µs. Such quasi-single c-Cu 2 O wafers lead to efficient solar cells with an open-circuit voltage of 0.95 V and highly responsive photodetectors with superior cycling stability. These results indicate not only the advancement of fabricating high-quality Cu 2 O wafers upon controllable methodology but also the promising optoelectronic applications using p-type metal oxide semiconductors.

Internally hollow Cu2O nanoframes with the abundance of {110} facets achieves triple-win in direct propylene epoxidation

“…3 demonstrated that while the emission spectra of various Cu 2 O samples were similar, the relative intensity of s-Cu 2 O-NF was higher compared to both s-Cu 2 O and s-Cu 2 O-NC under 450 nm illumination. This observation accounted for the gradual darkening of the sample color throughout the etching processes, indicating a consequent alteration in the band gap of the Cu 2 O sample 9,35 . These observations can be explained by three distinct stages in the crystal growth and etching process 24,36 : (1) the reaction of Cu 2+ and OH − leading to Cu(OH) 2 precipitation; (2) the addition of NH 2 OH•HCl accelerated the conversion of Cu(OH) 2 precipitates into Cu 2 O nanocrystals with trace Cl − incorporating into the crystal lattice 9 ; (3) morphology control by the ligandprotection/selective facet-etching strategy ensuring the predominant exposure of the {110} facets.…”

Enhanced photo-response performance of Cu2O-based graded heterojunction optoelectronic devices with a Ga2O3 buffer layer

“…On this basis, we drew a diagram of the energy-level arrangement. 16,37,38 As shown in Fig. 4j, the conduction band minimum of Ga 2 O 3 is located between those of Cu 2 O and ZnO, and the stepped energy band structure is conducive to charge transfer.…”

“…To gain further insight into the mechanism of the performance enhancement through the use of different architectures, we characterized the chargetransfer kinetics and charge recombination through the biased EQE spectra, electrochemical impedance spectroscopy (EIS), and capacitance-voltage (C-V) profiling. 37 Fig. 5d shows the ratio of EQE (À0.5 V) to EQE (0 V) as a function of the wavelength.…”

Fabricating High-Quality Cu2O Photocathode by Magnetron Sputtering: Insight into Defect States and Charge Carrier Collection in Cu2O

“…This should ensure that the carrier encounters as little scattering as possible by the defects during migration, thus increasing the carrier mobility. Besides, tracing back to the XRD and SEM information of Cu 2 O in Figure , ED-Cu 2 O has larger crystal grains than MS-Cu 2 O, which should help further alleviate the carrier scattering through grain boundaries, thereby enlarging the mobility, referring to Cu 2 O fabricated by the thermal oxidation method, which features a carrier mobility of 91 cm 2 V –1 s –1 with crystal grains up to a few micrometers and carrier density down to 1 × 10 13 cm –3 . , Thus, the carrier mobility of ED-Cu 2 O should be much greater than MS-Cu 2 O in theory. The experimental data, however, turn out to be the opposite.…”