In-situ heavily p-type doping of over 1020 cm−3 in semiconducting BaSi2 thin films for solar cells applications

Abstract

B-doped p-BaSi2 layer growth by molecular beam epitaxy and the influence of rapid thermal annealing (RTA) on hole concentrations were presented. The hole concentration was controlled in the range between 1017 and 1020 cm−3 at room temperature by changing the temperature of the B Knudsen cell crucible. The acceptor level of the B atoms was estimated to be approximately 23 meV. High hole concentrations exceeding 1 × 1020 cm−3 were achieved via dopant activation using RTA at 800 °C in Ar. The activation efficiency was increased up to 10%.

BaSi2as a promising low-cost, earth-abundant material with large optical activity for thin-film solar cells: A hybrid density functional study

“…2) Recently, this binary material has received much attention as it is a suitable absorber in thin-film solar cells. [3][4][5][6][7][8][9] Many promising properties, such as a suitable band gap in the range of 1.13-1.30 eV, large absorption coefficient (>10 4 cm ¹1 ), large quantum efficiency (>70%), long minority-carrier lifetime (11-14 µs) corresponding to the diffusion length on the order of 60 µm, and control of bipolar conductivity by means of impurity doping, have, to date, been reported for BaSi 2 . [3][4][5][6][7][8][9] Despite exhibiting these promising material characteristics and many experimental studies, the thin-film PV technologies based on BaSi 2 have not yet reached the device level.…”

“…On the other hand, for BaSi 2 , a film thickness of <1 µm is commonly used in various experimental studies. [3][4][5][6][7][8][9]22,26) However, it yields a band-gap energy of 1.3 eV. 22,26) In addition, sample quality, growth conditions, and impurities also affect the photoabsorption properties.…”

Analysis of the electrical properties of Cr/n-BaSi2 Schottky junction and n-BaSi2/p-Si heterojunction diodes for solar cell applications

“…To form BaSi 2 homojunction diodes, the properties of BaSi 2 thin-films doped with impurities such as Cu, Ag, Sb, P, As, In, Al, and B have also been investigated. [20][21][22][23][24][25][26] Among these elements, Sb and B were proved to be the suitable candidates for n þ -BaSi 2 and p þ -BaSi 2 , respectively. Their diffusion coefficients are another important parameter that should be taken into account.…”

Evaluation of potential variations around grain boundaries in BaSi2 epitaxial films by Kelvin probe force microscopy

“…11,12 Recent experimental results on large photoresponsivity, long minority-carrier lifetime, and conductivity control by impurity doping in the undoped n-BaSi 2 have spurred interest in this material. [13][14][15][16][17] In particular, the minority-carrier diffusion length, a key parameter determining the performance of solar cells, was found to be approximately 10 lm in the undoped n-BaSi 2 epitaxial film on Si(111) by means of an electron-beam-induced current technique. 18 This value is much larger than the grain size of the BaSi 2 ($0.2 lm), implying that the GBs do not work as defect centers for minority carriers (holes) in n-BaSi 2 .…”