Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Using radiant energy
Reexamination Certificate
2000-10-02
2002-11-12
Le, N. (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Using radiant energy
C324S537000, C324S754120, C324S072500
Reexamination Certificate
active
06479980
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thin film spin probe used on spin polarized scanning tunneling microscopes. More particularly, the present invention relates to a thin film spin probe that is capable of measuring the spin-polarized components parallel with and vertical to the surface of a specimen.
BACKGROUND TECHNOLOGY
A probe manufactured by cleaving semiconductor single crystals is used in an attempt to measure the spin-polarized components on specimen surfaces under a scanning tunneling microscope.
An example of measuring the spin polarized components using said probe is described referring to FIG.
6
. In
FIG. 6
,
101
is a probe manufactured by cleaving a semiconductor single crystal.
102
is a specimen for measuring spin-polarized components. The specimen
102
comprises a magnetic film
102
b
(specimen) which is sufficiently thin to allow the transmission of excitation light and a transparent board or a substrate
102
a
(glass, mica, etc.) supporting said magnetic film. To measure, excitation light is transmitted through and vertical to the specimen as shown in the figure. The transmitted light is irradiated on the probe
101
to detect spin polarization perpendicular to the surface of the specimen
102
b.
The problems encountered with this method are:
a) To optically excite the probe, excitation light must pass through the specimen from the thin specimen side. This limits the thickness of the specimen.
b) Because the probe that is manufactured by cleaving semiconductors is thick, even when light is irradiated from the probe side perpendicular to the surface of the specimen, the excitation light can penetrate only 1 &mgr;m into the surface at best, due to the large absorption constant. Efficient electron excitation at the tip cannot be expected.
c) Excitation light is incident from the probe side when measuring the components on the surface of a specimen (parallel components). Effective excitation is thus impossible because of the three-dimensional spread of the probe.
d) It is difficult to embed into a thin film spin probe a quantum structure designed to control spin polarization of excited electrons to enhance light emitting efficiency. It is therefore difficult to manufacture light emitting thin film spin probes.
With a view to solving these conventional problems, an object of the present invention is to provide a novel thin film spin probe by forming a thin GaAs/AlGaAs film on a GaAs board or a substrate using a thin film forming unit and by partly removing said substrate by selective etching.
The present invention further intends to solve the above problems by offering light emitting thin film spin probes comprising a GaAs substrate, a transparent support film made of AlGaAs, etc., formed on said substrate using a thin film forming unit, a thin film accommodating a light emitting region formed on said support film, and a thin barrier layer formed on said light emitting film, wherein said substrate is partly removed by selective etching.
DISCLOSURE OF THE INVENTION
The thin film spin probe of the present invention can be sufficiently thin as to allow excitation light to pass through it so that excitation light can be irradiated from the prober side, eliminating the restriction on the thickness of specimens to be measured.
It is also possible to alleviate the magnetic circular two-color effects that occur when the specimen excitation light is transmitted.
It is possible, by using semiconductor hetero-junction manufacturing technology, to embed a structure to effectively contain excitation carriers or a structure to control spin polarization.
Thin film spin probes are generally effective also for measuring the spin-polarized components that are horizontal with the surface of a specimen. In such an application, the thin film spin probes with a semiconductor hetero-junction can effectively contain carriers and alleviate the reduction in polarization that is one of the problems with single crystal cleaved probes.
As for light emission that is difficult to detect with a single crystal cleaved probe, the use of the quantum well structure enhances the efficiency of light emission. It is thus possible to measure spin polarization with a high sensitivity.
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Sueoka, Kazuhisa et al.The Study of a Thin GaAs Tip.Hyomen Kagaku, vol. 19, No. 8: pp. 522 to 526, 1998.
Kimura, M. et al.Measurement of Spin-Relaxation Times by Time-Resolved Photoluminescence.Journal of Applied Magnetics Association of Japan, vol. 20, No. 2:p. 253-256, 1996.
Agency of Industrial Science and Technology
Le N.
Rader & Fishman & Grauer, PLLC
Sundaram T. R.
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