Abstract
The demand for high efficiency intermediate band (IB) solar cells is driving efforts in producing high quality IB photovoltaic materials. Here, we demonstrate ZnTe:O highly mismatched alloys synthesized by high dose ion implantation and pulsed laser melting exhibiting optically active IB states and efficient sub-gap photoresponse, as well as investigate the effect of pulsed laser melting on the structural and optical recovery in detail. The structural evolution and vibrational dynamics indicates a significant structural recovery of ZnTe:O alloys by liquid phase epitaxy during pulsed laser melting process, but laser irradiation also aggravates the segregation of Te in ZnTe:O alloys. A distinct intermediate band located at 1.8 eV above valence band is optically activated as evidenced by photoluminescence, absorption and photoresponse characteristics. The carrier dynamics indicates that carriers in the IB electronic states have a relatively long lifetime, which is beneficial for the fast separation of carriers excited by photons with sub-gap energy and thus the improved overall conversion efficiency. The reproducible capability of implantation and laser annealing at selective area enable the realization of high efficient lateral junction solar cells, which can ensure extreme light trapping and efficient charge separation.
Highlights
High lattice crystal quality and producing a high impurity trapping that surpasses the equilibrium solid solubility limit[17,18]
In the ω-scan rocking curves shown in Fig. 1(b), the shoulder feature at the low-angle side is more distinguished as the ω-scan method is highly sensitive to the short-range-order scattering caused by the scattering from local Bragg diffractions of agglomerated point defects or structural grain boundaries[19]
As calculated by the Stopping and Range of Ions in Matter (SRIM) software, the implanted layer has extremely high vacancy concentration of about 1022 cm−3 within the projected range of 550 nm, which is beyond the critical dose for amorphization of ZnTe due to ion bombardment effect
Summary
High lattice crystal quality and producing a high impurity trapping that surpasses the equilibrium solid solubility limit[17,18]. The degree of properties recovery and thermal diffusion of dopants are strongly dependent on the condition of pulse laser melting. The PLM processes have been optimized on O-implanted ZnTe with extra high dose to achieve high crystalline quality and formation of optically active intermediate band. The crystalline and optical recovery has been assessed by various means and the carrier dynamics related to intermediate band has been investigated in details as well
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
