Evaluation of oxygen precipitation behavior in n-type Czochralski-Si for photovoltaic by infrared tomography: Effects of carbon concentration and annealing process conditions

Abstract

In this study, we evaluated the effects of carbon and annealing process conditions on the oxygen precipitation in an n-type Czochralski (Cz) wafer for solar cells by infrared light scattering tomography (IR-LST). It was confirmed that precipitates grow larger and denser as carbon concentration increase. Thus, carbon promotes oxygen precipitation. We also evaluated the effect of oxygen precipitation on the minority carrier lifetime by photoluminescence (PL) imaging. It was confirmed that the interface between the precipitate and the Si matrix is a dominant recombination center since the surface area of the precipitate obtained by IR-LST measurement and the PL intensity show good correlation. In addition, it was also confirmed that carbon is involved in the supply of interstitial oxygen to precipitates through the formation and extinction of the thermal donor. We believe that it is important to understand and control the effect of carbon of controlling the oxygen precipitation behavior.

Effects of surface recombination and excitation power on quantitative analysis of carbon in Si using room-temperature photoluminescence after electron irradiation

“…1) Although a great effort has been made to reduce the carbon concentration down to lower than 5 × 10 15 cm −3 in highquality Si wafers, further reduction is required recently for high-performance power devices such as insulated gate bipolar transistors 2,3) and high-efficiency solar cells with conversion efficiency close to the theoretical limit. 4,5) Since this concentration range is below the detection limit of the standardized IR absorption method, 6,7) the photoluminescence (PL) activation method using electron irradiation has attracted considerable attention as a technique for the lowlevel carbon quantification. [8][9][10][11][12][13] The PL method has been generally carried out at liquid He temperature (4.2 K) for the detection of the C-line (0.79 eV) and G-line (0.97 eV).…”

Oxygen Precipitation Behavior in n-Type Cz-Si Related to Carbon Concentration and Crystal Growth Conditions

“…Moreover, in combination with metal contamination, it may have an even greater negative effect on solar cell performance. [10][11][12][13] In addition, it has been reported that not only oxygen atoms, but also incorporated carbon is involved in this oxygen precipitation process. Carbon atoms in silicon crystals promote oxygen precipitation as nucleation centers and affect the precipitate density and size.…”

Effect of oxygen precipitation through annealing process on lifetime degradation by Czochralski-Si crystal growth conditions

“…boron diffusion and electrode formation) are added in the solar cell manufacturing process, and oxygen precipitation progresses. [2][3][4][5][6][7] The oxygen precipitate acts as a carrier recombination center, 4,5,[7][8][9][10][11][12][13][14][15][16][17][18][19][20] which can be the cause of reduction in solar cell conversion efficiency. In addition, it has been reported that not only oxygen, but carbon is involved in the oxygen precipitation.…”

“…3,6,17,[21][22][23][24][25][26][27] It has also been reported that there is a clear correlation between carbon concentration and precipitate density, implying that carbon promotes oxygen precipitation. [3][4][5] Therefore, in order to improve solar cell conversion efficiency, it is important to understand and control the oxygen precipitation behavior.…”