Determination of bulk diffusion lengths for angle-lapped semiconductor material via the scanning electron microscope: A theoretical analysis
Abstract
A standard procedure for the determination of the minority carrier diffusion length by means of a scanning electron microscope (SEM) consists in scanning across an angle-lapped surface of a P-N junction and measuring the resultant short circuit current I sub sc as a function of beam position. A detailed analysis of the I sub sc originating from this configuration is presented. It is found that, for a point source excitation, the I sub sc depends very simply on x, the variable distance between the surface and the junction edge. The expression for the I sub sc of a planar junction device is well known. If d, the constant distance between the plane of the surface of the semiconductor and the junction edge in the expression for the I of a planar junction is merely replaced by x, the variable distance of the corresponding angle-lapped junction, an expression results which is correct to within a small fraction of a percent as long as the angle between the surfaces, 2 theta sub 1, is smaller than 10 deg.
- Publication:
-
Unknown
- Pub Date:
- May 1978
- Bibcode:
- 1978dbdl.rept.....V
- Keywords:
-
- Diffusion Coefficient;
- Electron Microscopy;
- Minority Carriers;
- Semiconductor Junctions;
- Electric Current;
- Flat Surfaces;
- P-N Junctions;
- Partial Differential Equations;
- Solid-State Physics