DEVICE RESEARCH CONFERENCE 1255

mojunction), 2) Active layer thickness and 3) Type and concentration of active layer dopant. Devices have been examined with active layer thicknesses over the range of 1 to 6 microns. The dopants which have been used are germanium, tellurium, tin, and silicon. The results that have been obtained can be summarized as follows: 1) The distortion versus dc bias characteristics of double het- erostructure devices with different dopants are similar when the diffusion length of the minority carriers is greater than the active layer width. 2) Single hetero and homojunction devices are more linear than double heterostructure devices of comparable doping and active layer thickness. The total harmonic distortion measured on a single hetero or homojunction device was found to be 20 dB below that of a double heterostructure device of similar active layer thickness and doping, provided that the diffusion length of mi- nority carriers was greater then the active layer thickness. 3) The linearity of double heterostructure diodes was found to improve as the active layer thickness was increased.

These results have been interpreted in terms of the effect of carrier confining potential on the minority carriers in the active layer of the device.

IIIB-4 A Blue Light Emitting ZnSe LED Using a Double Heterojunction Approach-R. J. Robinson and Z. K. Kun, Zenith Radio Corporation, Chicago, IL 60639.

Room temperature, band edge emission in conductive ZnSe containing added sodium has recently been reported from pho- toluminescence studies.l The total emission consists of two bands: the first is the standard deep level emission while the second is a narrow band around the band edge quite similar to that observed in Group 111-Group V compounds. We have also observed the band edge emission at room temperature but in sodium doped ZnSe LED’s. Although the total emission is still a combination of two bands, the fraction of near band-to-band emission is enhanced over that reported in the earlier photolu-

‘mineseence studies.l The structure of the blue emitting LED’s consists of a vapor phase ZnSe epitaxy layer sandwiched between a zinc sulfoselenide substrate and a zinc sulfoselenide vapor phase epitaxy outer layer. The LED’s are made as described previous- ly2J using indium diffusion into n-type material followed by a zinc-indium conversion step. The essential point is that band edge emission at 4710 angstroms has been observed in a LED at room temperature in an optically confined ZnSe which is a direct band gap material.

paper we review the development of BH lasers along with some recent results to show further feasibility of these lasers.

The first successful operation of BH lasers was reported in 1974.2 Since then, the unique properties of these lasers have been unveiled, such as the low current operation in the mA range,5 the reproducible and stable fundamental mode operation,2 and cw operation with a p-side-up bonding.6 Besides, the technique used in fabrication of BH lasers can be used to make such optical de- vices and components as BH distributed feedback (DFB) lasers? waveguides and couplers.

One of our main efforts at present is to make sure how reliable these lasers can be. Preliminary lifetest results show that they are as reliable as usual double-heterostructure (DH) lasers. CW lifetime at room temperature over 3000 hours has been ob- tained.

Measurements of the time response ghow that delay time of narrow BH lasers is substantially shorter than that of DH lasers. Time responses of BH, DH, and DFB lasers are described and compared.

Due to the isotropic beam divergence of BH lasers, they can be used as light sources in such application fields as optical communication and holographic reconstruction with a simple optical system configuration. Reconstructed images of holograms will be presented.

Devices, B6-2, Tokyo, 1975.

1975.

City, 1976.

T. Tsukada, K. Saito, N. Shige, and Y. Shima, Digest 7th Conf. on Solid-state

T. Tsukada and Y. Shima, IEEE J. Quantum Electron, vol. QE-11, p. 494,

T. Tsukada, Digest Topical Meeting on Integrated Optics, MA-3, Salt Lake

IIIB-6 Channeled Substrate Buried Heterostructnre (GaAl) As Injection Lasers--P. A. Kirkby, D. F. Lovelace and G. H. B. Thompson, Standard Telecommunication Laboratories, Harlow, Essex, England CM179NA.

A technique for fabricating stripe geometry GaAs/(GaAl)As injection lasers with optical and carrier confinement not only in the plane perpendicular but also parallel to the p-n junction is reported. This independently developed channeled substrate technique is a simple extension of conventional liquid phase epitaxy requiring no regrowth and relies on the strong tendency of epitaxial layers to smooth out as they grow.

The active regions of the preliminary 10 and 20 gm wide stripe lasers that have been fabricated to date are parabolic in cross section, tapering gradually to zero at the edges and completely embedded in GaAlAs. Unlike the “etched buried heterostructure lasers” recentlv reDorted bv Burnham and Scifres. the n- (GaA1)As layer is continuous thus preventing the direct injection of carriers into the substrate. Room temperature pulsed threshold

30%.

J. C. Bouley et al., J . Appl. Phys., vol. 46, p, 3549, 1976. 2 R. J. Robinson and 2. K. Kun, Appl . Phys. Let t . , vol. 21, p. 14,1976. 3 Z. K. Kun and R. J. Robinson, J . Electron. Mater. 5, p. 23,1976. currents are in the range 150-350 mA with efficiencies up to

-.

This paper describes the LPE growth techniques that we used

Injection lasers will be conveniently used in various ap- vors low order transverse mode operation close to threshold in plication fields if their active regions have unity aspect ratio. the multimode waveguides which we produced. Finally we report Recent efforts towards this direction have been very successfu~ the CW operation of these lasers and discuss the more significant to yield “buried-heterostructure” (BH) injection lasers?-4 In this aspects Of their Operation’

Present address: Cornell University, Ithaca, NY 14853. T. Tsukada, J . Appl. Phys., vol. 45, p. 4899,1974.

IIIB-7 Leaky Wave Room Temperature Double Hetero-

4 P. A. Kirkby, D. F. Lovelace, and G. H. B. Thompson, Digest Topical Meeting Burnham and W. Streifer, Xerox Palo Alto Research Center, Palo 3 R. D. Burnham and D. R. Scifres, Appl . Phys. Lett., vol. 27, p. 510,1975. structure GaAs:GaAIAs Diode Laser-D‘ R‘ Scifres9 R’ D’

on Integrated Optics, PD-7, Salt Lake City, 1976. Alto, CA 94304.