JPS6282331A - Photodetector for measuring luminescence patterns - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] As a method of efficiently receiving light emitted from a light-emitting substance, a through hole is provided in the center of a light receiving element, and an excitation beam is projected onto a substrate through this through hole and the light is received.

[Industrial application field]

The present invention relates to a structure of a photodetector for measuring light emission patterns with improved collection efficiency.

Gallium arsenide (GaAs) + indium phosphide (InP)
When radiation with energy higher than the energy gap is projected onto a semiconductor material with a direct transition type band structure, such as mercury cadmium tellurium (IIgCdTe),
Electrons are excited to the conduction band, and the excited electrons and holes generated in the valence band directly recombine, resulting in light emission.

In addition, these semiconductor crystals contain vacancies, interstitial atoms,
It contains crystal defects such as dislocations, impurity atoms, etc., and light emission also occurs when localized levels caused by these become emission centers and emit transition energy that is sufficiently larger than the energy of phonons.

However, when the localized level is low and the transition energy is close to the phonon energy, or when the interaction between the electron and the lattice is large, no light is emitted.

Taking advantage of this phenomenon, the distribution of light emission patterns from a semiconductor substrate is measured using a light-receiving element, and information on dull objects, transitions, etc. is investigated.

The present invention relates to the structure of such a photodetector.

[Conventional technology]

FIG. 2(A) is a cross-sectional view showing the structure of a conventional photodetector, and FIG. 2(B) is a perspective view of a light receiving element used therein.

In other words, when an excitation beam 2 such as a laser beam or an electron beam is projected onto a substrate 1 made of a luminescent material such as IgCdTe or GaAs and scanned, the light 3 emitted from the substrate 1 is emitted all over the surface. As shown in the figure, the photodetector has a light-receiving element 4 placed at an inclined position with respect to the substrate 1 to receive a part of the emitted light 3, and a reflection tIL5 is installed at a position opposite to the light-receiving element 4. The reflected light 6 is configured to be incident on the light receiving element 4.

However, in this conventional structure, there is a problem in that only a portion of the light 3 emitted by the projection of the excitation beam 2 onto the substrate enters the light receiving element 4, and adjustment of the reflection V15 is complicated.

As shown in FIG. 4B, the light-receiving element 4 has a light-receiving material 8 made of a p-n junction arranged in a transmission window 7 made of quartz or sapphire, and a lead wire 9 is provided through an extraction electrode. It has a structure.

[Problem that the invention seeks to solve]

As described above, conventional photodetectors have problems in that they have poor light collection efficiency, are troublesome to adjust the reflecting mirror, and require a considerable amount of space.

[Means for solving problems]

The above problem is solved by using a photodetector that scans an excitation beam across a substrate made of a luminescent material and measures the luminescence distribution of the substrate using a light receiving element, which is provided with a through hole in the center of the light receiving element. This problem can be solved by using a photodetector for measuring a light emission pattern, which has a structure in which an excitation beam is projected onto a substrate to be processed through the substrate, and the light emitted from the substrate is received over the entire area of the device.

[Effect]

In the present invention, as a method of improving light collection efficiency, a through hole is provided in the center of the light receiving element, and the substrate can be scanned with an excitation beam through the through hole.

With such a structure, it is possible to bring the light receiving element closer to the substrate than in the past, so that most of the emitted light can be received, and a reflecting mirror is not required.

〔Example〕

FIG. 1(A) is a sectional view of a photodetector according to the present invention, and FIG. 1(B) is a perspective view, and the light receiving element is also a photodetector.

That is, the photodetector 10 according to the present invention has a transmission window 7. which constitutes a conventional light receiving element. A through hole 12 is provided in the center of the light receiving material 8 and the case 1) housing them, and the substrate 1 is scanned through this through hole 12.

With such a configuration, the photodetector 10 can be brought close to the substrate 1, and therefore weak light emission can be detected.

Example 1: A pn junction element made of silicon (Si) with an area of 5×5 was used as the light-receiving material 8, and a through hole with a diameter of 1 was provided in it so that an excitation electron beam could pass therethrough.

On the other hand, using an InP substrate formed by vapor phase epitaxial growth as a substrate, cathodoluminescence (abbreviated as CL) was used.
) pattern measurements were performed.

Here, the acceleration voltage of the electron beam was set to 20 to 30 KV.

As a result, we were able to detect a large number of spot-like non-light-emitting areas that were generated during vapor phase epitaxial growth.

Example 2: Using the photodetector of Example 1, a CL pattern was measured on a GaAs substrate obtained by liquid phase epitaxial growth under similar measurement conditions.

As a result, LEC (Liquid Encapsul
We were able to clarify the cell structure of the light-emitting pattern related to dislocations on a substrate fabricated using the Czochralski method.

〔Effect of the invention〕

As described above, according to the present invention, not only weak light emission can be detected due to improved light collection efficiency, but also a light emission pattern can be easily measured because a reflecting mirror is not required.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view (A) and a perspective view (B) of a photodetector according to the present invention, and Fig. 2 is a cross-sectional view (A) of a conventional photodetector and a perspective view of a light-receiving element used therein. Figure (B). In the figure, 1 is a substrate, 2 is an excitation beam, 3 is emitted light, 4 is a light receiving element, 5 is a reflecting mirror, 6
is reflected light, 7 is a transmission window, 8 is a light receiving material, IO is a photodetector, and 12 is a through hole.

Claims (1)

[Claims] A photodetector that scans a substrate (1) made of a luminescent substance with an excitation beam (2) and measures the luminescence distribution of the substrate (1) using a light receiving element (4), comprising: The detector has a through hole (12) in the center of the light receiving element (4).
is provided, the excitation beam (2) is projected onto the substrate (1) through the through hole (12), and the element receives the light (3) emitted from the substrate (1). A photodetector for measuring luminescence patterns.