Editing Scanning probe microscopy (section)

== Scanning photo current microscopy (SPCM) ==
SPCM can be considered as a member of the Scanning Probe Microscopy (SPM) family. The difference between other SPM techniques and SPCM is, it exploits a focused laser beam as the local excitation source instead of a probe tip.<ref>{{Cite journal |last1=GRAHAM |first1=RION |last2=YU |first2=DONG |date=2013-09-23 |title=Scanning Photocurrent Microscopy in Semiconductor Nanostructures |url=http://dx.doi.org/10.1142/s0217984913300184 |journal=Modern Physics Letters B |volume=27 |issue=25 |pages=1330018 |doi=10.1142/s0217984913300184 |bibcode=2013MPLB...2730018G |issn=0217-9849|url-access=subscription }}</ref>

Characterization and analysis of spatially resolved optical behavior of materials is very important in opto-electronic industry. Simply this involves studying how the properties of a material vary across its surface or bulk structure. Techniques that enable spatially resolved optoelectronic measurements provide valuable insights for the enhancement of optical performance. Scanning electron microscopy (SPCM) has emerged as a powerful technique which can investigate spatially resolved optoelectronic properties in semiconductor nano structures.

=== Principle ===
[[File:Laser scan of the scanning photocurrent microscope.png|thumb|Laser scan of the scanning photocurrent microscope]]

In SPCM, a focused laser beam is used to excite the semiconducting material producing excitons (electro-hole pairs). These excitons undergo different mechanisms and if they can reach the nearby electrodes before the recombination takes place a photocurrent is generated. This photocurrent is position dependent as it, raster scans the device.

=== SPCM analysis ===
Using the position dependent photocurrent map, important photocurrent dynamics can be analyzed.

SPCM provides information such as characteristic length such as minority diffusion length, recombination dynamics, doping concentration, internal electric field  etc.