Liquid phase epitaxial (LPE) grown junction In1x Ga x P (x0.63) laser ofwavelength 5900 (2.10 eV, 77K)W. R. Hitchens, N. Holonyak Jr., M. H. Lee, J. C. Campbell, J. J. Coleman, W. O. Groves, and D. L. Keune Citation: Applied Physics Letters 25, 352 (1974); doi: 10.1063/1.1655505 View online: http://dx.doi.org/10.1063/1.1655505 View Table of Contents: http://scitation.aip.org/content/aip/journal/apl/25/6?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Narrow band gap (1eV) InGaAsSbN solar cells grown by metalorganic vapor phase epitaxy Appl. Phys. Lett. 100, 121120 (2012); 10.1063/1.3693160 15% efficiency (1 sun, air mass 1.5), largearea, 1.93 eV Al x Ga1x As (x=0.37) np solar cell grown bymetalorganic vapor phase epitaxy Appl. Phys. Lett. 52, 631 (1988); 10.1063/1.99387 Lowthreshold LPE In1xGa xP1z As z/In1x Ga x P1z As z /In1 x Ga xP1zAs z yellow doubleheterojunction laser diodes (J4 A/cm2, 5850 , 77K) Appl. Phys. Lett. 27, 245 (1975); 10.1063/1.88410 Liquid phase epitaxial In1x Ga x P1z As z /GaAs1y P y quaternary (LPE)ternary (VPE) heterojunctionlasers (x 0.70, z 0.01, y 0.40; Appl. Phys. Lett. 25, 725 (1974); 10.1063/1.1655377 Resonant enhancement of the recombination probability associated with isoelectronic trap states insemiconductor alloys: In1x Ga x P:N laser operation (77 K) in the yellowgreen (5560 ,2.23 eV ) J. Appl. Phys. 43, 5134 (1972); 10.1063/1.1661085
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Liquid phase epitaxial (LPE) grown junction In 1 -x Gax P (X"" 0.63) laser of wavelength A'" 5900 A (2.10 eV, 77K)*
W. R. Hitchens, N. Holonyak Jr., M. H. Lee, J. C. CampbeW, and J. J. Coleman
Deparrment of Electrical Engineering and Materials Research Laboratory. University of Illinois at Urbana-Champaign. Urbana, Illinois 61801
W. O. Groves and D. L. Keune
Monsanto Company, St. Louis, Missouri 63166 (Received 21 May 1974; in final form 17 June 1974)
Laser operation (77 OK) of In1_xGaxP LPE p-n junctions is demonstrated at A~5900 A (2.10 eV, yellow). The junctions are prepared by the sequential growth (on GaAs1_yPy substrates) of first an n -type layer and then a Zn-doped p -type layer (not compensated). During growth of the p -type layer, Zn diffuses slightly (at reduced concentration) into the first layer, yielding a thin compensated active layer. The structure which results approximates in operation the behavior of a single heterojunction. Although the threshold for the laser operation of these devices is fairly high, it is demonstrated, nevertheless, that In1_x Gax P LPE grown junctions can be operated as lasers and, furthermore, at wavelengths A ;S; 5900 A.
Apart from one report of Zn-diffused In1_xGaxP (x - O. 27) laser junctions operating (77 OK) at A -7600 A (crystal grown at constant temperature from solution)l and a second report of vapor phase epitaxial (VPE) grown junction Inl_xGaxP (x - 0.57) lasers operating at A~6105 A (77 OK), 2 there has been no further report of the successful operation of a homo- or heterojunction laser in Inl_xG~P, not to mention at wavelengths shorter than 6000 A. Diode laser operation of In1_xGaxP has proven to be a notoriously difficult problem, probably, as we discuss elsewhere, 3 because of the large lattice mismatch between the two binary constituents InP (5.869 A) and GaP (5.451 A), the resulting need for careful control of the ternary crystal composition, the need for a good lattice match on any substrate crystal on which Inl_xG~P might be grown epitaxially, and probably also because of the peculiarities of impurity incorporation (impurity disturbances) in such a ternary Wide-gap system. For example, it is a simple matter to diffuse Zn into the n-type ternary GaAs1_xPx and make a junction laser, 4 but it is not so straightforward to ap-ply this Simple procedure to n-type Inl_xG~P, 1 which is otherwise known to be of laser quality5,6 and capable of photopumped pulsed laser operation even at room tem-perature. 7 Apparently Zn diffusion into Inl_xG~P can severely disturb the In-Ga sublattice. 4 Also, in spite of the fact that thin layers (- 1 J.!.) of x z O. 52 Inl_XG~P (doped or undoped) can be grown (LPE) between wider-gap n-type and p-type AlyGa1_yAs to form a double het-erojunction, this does not turn out to be an easily grown device, although in principle it should be possible to build. B Despite its intractable character, in this paper we describe the sequential LPE growth of two-layer homojunction Inl_xG~P (x - 0.63) lasers that operate (77 0 K) at a wavelength - 5900 A (yellow). The layer dopings are chosen to give an approximation to the carrier-confinement behavior of a single heterojunction. 9
Following a procedure described extensively recent-ly, 3,6 we grow first, by constant-temperature LPE (- 800 0 C, open tube furnace), a laser-quality n -type Inl_xG~P layer on a lattice-matched GaAs1_"Py substrate (x:::; O. 49y + 0.52). In the present work we have employed y '" O. 25 GaAs1_yPy substrates and grow x'" O. 63 Inl_xG~P.
352 Applied Physics Letters, Vol. 25, No.6, 15 September 1974
This chOice of substrate is somewhat arbitrary and can be higher in GaP concentration, permitting higher com-position Inl_xG~P to be grown. To grow the initial n-type layer, we employ a cylindrical graphite boat with removable end caps and a melt conSisting typically of 21 g of In, 0.48 g of InP, 0.23 g of GaP, and 10 mg of SeoThe melt is fir~t saturated at 800C, then is cooled and the substrate crystal is placed off-center at one end. After reheating and a 5-10 c cool down to effect supersaturation, the boat is rotated to permit the melt to contact the substrate and grow an n -type Inl_ .. G~P layer.
The ,layer is polished and etched, and the process is repeated with -100 mg of Zn replacing the Se doping. This results in the growth of an uncompensated p -type layer, with the melt serving also as a dilute Zn source permitting Zn diffusion into 1-2 J.!. of the initial n-type layer and thus creating a thin compensated layer-the active layer of the device.
A cleaved and etched cross section of the final struc-ture that results is shown in Fig. L The etchant used (for decoration) is similar to that mentioned previous-ly.5 Although it is not readily apparent in Fig. 1, under microscopic examination the compensated region, labeled p on, can be readily distinguished, Under photo-excitation this layer becomes strikingly apparent, If the cleaved surface is uniformly photoexcited by an Ar+ laser (77 0 K), the n- and p -Inl_xG~P layers glow (pale yellow) at nearly the same brightness and the thin p-n region appears as a bright layer shifted slightly in color toward the orange -yellow. If the Ar+ laser is focused to the limit as a probe excitation source, the n region exhibits a peak emiSSion at 2.159 eV, the p region at 2.130 eV, and thep-n region at 2.105 eV-and at 2x greater intensity than either the p or n regions. As the photoexcitation probe reveals, the empty donor band tail in the p -n region has the same effect as a reduction in bandgap in this region. Furthermore, the compensat-ed region clearly exhibits wave guiding effects. Photo-excitation of a spot on the p-n lasrer produces lumines-cence in the entire compensated layer, while neither of the adjacent layers is observed to glow. Thus, the
Copyright 1974 American Institute of Physics 352 This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
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x '" 0.63 )' '" 0.25
FIG. 1. Cleaved and etched Fabry-Perot face of an In1_xGaxP p-n junction laser "grown by liquid phase epitaxy (LPE). The region labeledp-n is a thin (1-2 1') compensated (Zn-Se) layer formed when the p layer is grown (LPE) on the n layer. The circular mottled areas are due to etching and cannot be cor"-related with any crystal defects.
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