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Controlled Emission in Heterojunction Structures

IP.com Disclosure Number: IPCOM000089612D
Original Publication Date: 1977-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Chang, LL: AUTHOR [+3]

Abstract

A periodic heterojunction structure can be made of two semiconductors having a specific band-edge relationship such that its optical properties, emission and absorption, are ccntrolled by an electric field applied perpendicularly to the plane of the layers.

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Controlled Emission in Heterojunction Structures

A periodic heterojunction structure can be made of two semiconductors having a specific band-edge relationship such that its optical properties, emission and absorption, are ccntrolled by an electric field applied perpendicularly to the plane of the layers.

Fig. 1 shows such a structure, and Fig. 2 shows the related energy diagram. The band discontinuities E(c1) - E(c2) and E(v1) - E(v2), create a periodic potential (Fig. 2A). With illumination, labeled h Nu(i), electrons and holes are generated and relaxed to their respective, energetically favorable positions. Potential wells occur in the conduction band for electrons, and potential wells occur in the valence band for holes. The spatial separation results in a quasi- stable situation where the carriers are accumulated with little spontaneous recombination (Fig. 2B). The application of an external disturbance, such as an electric field, or radiation with h Nu < E(o), etc., would, as shown in Fig. 2C, greatly enhance their recombination rate and cause intense emission at h Nu(o) >/~ E(o). Thus, an efficient light-emitting diode and possibly, with proper cavity arrangement, a laser with relatively large power may be constructed.

The description thus far has been based on "bulk" layers. Where the layers are sufficiently thin, quantum states are formed in the conduction and valence bands. In this case, emission between those states can be controlled by the layer thick...