Evolution of Bulk c-Si Properties during the Processing of GaP/c-Si Heterojunction Cell

Physica Status Solidi (a)

et al. 2019

The capability of plasma‐enhanced atomic layer deposition (PE‐ALD) for the formation of GaP nucleation layers on Si substrates for further epitaxial growth is explored. The possibility of epitaxial growth of GaP by metalorganic vapor phase epitaxy (MOVPE) on templates prepared by PE‐ALD GaP/Si is demonstrated. The structural and electronic properties of the interfaces between the GaP nucleation layer and the Si substrate as well as their thermal stability are studied. Initially, the GaP/Si structures obtained by PE‐ALD without additional hydrogen plasma exhibit better photoelectric properties compared with that fabricated with high H2 plasma power that induces the formation of defects in the silicon subsurface layer. Annealing at temperatures of 550–600 °C leads to a decrease in the defect concentration created by the hydrogen plasma. Thus, after annealing, the GaP/Si interfaces fabricated by both types of PE‐ALD processes exhibit similar quality. Thermal treatment of the GaP/Si structures at temperatures of 725–750 °C leads to the diffusion of phosphorus from GaP into Si and to the formation of an isotype n‐GaP/n–p‐Si heterojunction with improved photoelectric properties. High‐temperature stability of the GaP/Si interface fabricated by PE‐ALD is essential for its prospective use for GaP/Si templates.

Section: Electrical Properties Of the Gap/si Interfacesupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Study of GaP Nucleation Layers Grown on Si by Plasma‐Enhanced Atomic Layer Deposition

Physica Status Solidi (a)

et al. 2019

“…On the other hand, electrons can easily overpass the spike formed by small DE C. 5 However, high temperatures which are commonly used for GaP growth using conventional techniques such as molecular beam epitaxy (MBE) and metal organic vapor-phase epitaxy (MOVPE) lead to lifetime degradation in the Si wafers. 6,7 Recently, we have demonstrated that growth of GaP by plasma-enhanced atomic layer deposition (PE-ALD) at relatively low temperature (below 400 C) does not affect Si substrate quality. 7 However, an n-type GaP layer is required for the fabrication of n-GaP/p-Si heterojunctions.…”

Section: Introductionmentioning

confidence: 99%

Si doped GaP layers grown on Si wafers by low temperature PE-ALD

Journal of Renewable and Sustainable Energy

et al. 2018

Low-temperature plasma enhanced atomic layer deposition (PE-ALD) was successfully used to grow silicon (Si) doped amorphous and microcrystalline gallium phosphide (GaP) layers onto p-type Si wafers for the fabrication of n-GaP/p-Si heterojunction solar cells. PE-ALD was realized at 380 C with continuous H 2 plasma discharge and the alternate use of phosphine and trimethylgallium as sources of P and Ga atoms, respectively. The layers were doped with silicon thanks to silane (SiH 4) diluted in H 2 that was introduced as a separated step. High SiH 4 dilution in H 2 (0.1%) allows us to deposit stoichiometric GaP layers. Hall measurements performed on the GaP:Si/p-Si structures reveal the presence of an n-type layer with a sheet electron density of 6-10 Â 10 13 cm À2 and an electron mobility of 13-25 cm 2 V À1 s À1 at 300 K. This is associated with the formation of a strong inversion layer in the p-Si substrate due to strong band bending at the GaP/Si interface. GaP:Si/p-Si heterostructures exhibit a clear photovoltaic effect, with the performance being currently limited by the poor quality of the p-Si wafers and reflection losses at the GaP surface. This opens interesting perspectives for Si doped GaP deposited by PE-ALD for the fabrication of p-Si based heterojunction solar cells.

“…12 The use of high temperatures could lead to interdiffusion of group-III and -V atoms into Si and opposite, which act as dopants affecting the electrical properties of heterojunctions, and it can also promote the fast diffusion of species that can degrade the carrier lifetime in c-Si. 13 In this paper, we explore a low temperature (less than 400 C) technological approach for the growth of III-V compounds on Si substrates using plasma-enhanced atomic layer deposition (PE-ALD) approach. The PECVD related lowtemperatures technology could provide a lot of advantages for PV mass production such as large area, high throughput, low price of the equipment, and the process.…”

Section: Introductionmentioning

confidence: 99%

Low temperature plasma enhanced deposition of GaP films on Si substrate

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

et al. 2017

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