Method and apparatus for thin film quality control

A method of a photovoltaic thin film quality control, said method comprising:

• illuminating one or more discrete sampled points of a stack of thin layers forming a photovoltaic panel;
• determining the spectral composition of the illumination reflected by the sampled points;
• deriving from the spectral composition at least one of a group of the photovoltaic thin film parameters consisting of the thin film thickness (d), thin film refractive index (n), thin film extinction coefficient (k), thin film surface roughness, crystallinity, energy gap, phase composition, conductivity, stoichiometry, and
• wherein locations of the sampled points are selected such that each sampled point contains a partial layer stack.

An apparatus for accurate measurement of a stack of thin films parameters, said apparatus comprising:

• a support operative to support and move a photovoltaic panel comprising a stack of thin films, said support enabling to illuminate the stack from a first side and a second side;
• one or more measurement units including a polychromatic or monochromatic illumination device operative to illuminate the stack of thin films;
• and
• at least one detector operative to detect collected illumination from the stack of the thin films;
• a controller operative to receive the value and wavelength of the collected illumination, determine at least one of thin film optical characteristics in a sampled point where the stack has a reduced number of thin film layers, combine said characteristics into an optical model of the full stack, and determine optical parameters of the full stack.

A method of scribe line location detection, said method comprising:

• identifying at least one scribe location;
• obtaining from a control system the distance between the scribe lines;
• determining the time of the next crossing of a measurement unit field of view;
• and
• performing the measurements in the scribe line.

A method of a photovoltaic thin film quality control, said method comprising:

• illuminating one or more discrete sampled points in a stack of thin layers forming a photovoltaic panel;
• selecting the sampled point location where the stack consist of a single thin layer;
• determining the spectral composition of the illumination reflected by the sampled points;
• deriving from the spectral composition at least one of a group of the photovoltaic thin film parameters consisting of the thin film thickness (d), thin film refractive index (n), thin film extinction coefficient (k), thin film surface roughness, energy gap, crystallinity, phase composition, conductivity and stoichiometry.

A method of a photovoltaic thin film quality control, said method comprising:

• illuminating one or more discrete sampled points located in scribe lines of a stack of thin layers forming a photovoltaic panel;
• following the scribe line location by introducing position feedback into measurement system;
• determining the spectral composition of the illumination reflected by the sampled points;
• and
• deriving from the spectral composition at least one of a group of the photovoltaic thin film parameters consisting of the thin film thickness (d), thin film refractive index (n), thin film extinction coefficient (k), thin film surface roughness, energy gap, crystallinity, phase composition, conductivity and stoichiometry.