A-Si:H Ambipolar Diffusion Length and Effective Lifetime Measured by Flying Spot Technique (FST)

ABSTRACTThe determination of the ambipolar diffusion length, L*, and the effective lifetime, τ*, in p/i and a-Si:H Schottky barriers (ITO/p/a-Si:H/Al-Si; Cr/a-Si:H/Cr/Ag) have been determined by Flying Spot Technique, FST. This technique consists in the transient analysis of the photocurrent/photopotential induced by a laser beam that moves perpendicularly to the structure with a constant motion ratio, at different velocities. Taking into account the competition between the diffusion/drift velocities of the excess carriers and the velocity of the flying spot, it is possible to solve the transport equations and to compute separately L* and τ*, from the asymmetrical distribution responses.

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A-Si:H ambipolar diffusion length and effective lifetime measured by flying spot (FST) and spectral photovoltage (SPT) techniques

Journal of Non-Crystalline Solids ◽

10.1016/s0022-3093(05)80159-0 ◽

1991 ◽

Vol 137-138 ◽

pp. 479-482 ◽

Cited By ~ 10

Author(s):

M. Vieira ◽

R. Martins ◽

E. Fortunato ◽

F. Soares ◽

L. Guimarães

Keyword(s):

Diffusion Length ◽

Ambipolar Diffusion ◽

Effective Lifetime ◽

Flying Spot

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Hydrogenated Amorphous Silicon Speed Sensor Based on the Flying Spot Technique

MRS Proceedings ◽

10.1557/proc-377-839 ◽

1995 ◽

Vol 377 ◽

Cited By ~ 3

Author(s):

M. Vieira ◽

A. Fantoni ◽

A. Maçarico ◽

F. Soares ◽

G. Evans ◽

...

Keyword(s):

Amorphous Silicon ◽

Material Characterization ◽

Diffusion Length ◽

Hydrogenated Amorphous Silicon ◽

Effective Lifetime ◽

Object Position ◽

The Past ◽

Speed Sensor ◽

Hydrogenated Amorphous ◽

Flying Spot

ABSTRACTIn the past we have developed a transient technique, called the Flying Spot Technique (FST). FST allows, not only to infer the ambipolar diffusion length but also the effective lifetime of the photogenerated carriers once the light spot velocity and geometry of the structure were known.In this paper, we propose to apply this technique backwards in order to detect the path and velocity of an object that is moving in the direction of a light source. The light reflected back from the object is analyzed through a p.i.n structure being the transient transverse photovoltage dependent on the movement of the object (position and velocity). Assuming that the transport properties of the material and the geometry of the device are known and using a triangulation method we show that it is possible to map the movement of the object. Details concerning material characterization, simulation and device geometry are presented.

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