of solidstate light emittershoweverthere is a specwith all commercia - PDF document

1 of solid-state light emitters;however,th
of solid-state light emitters;however,there is a spec-with all commercially available devices.tions,such as the use of plastic-optical Þbers,thatrequire green lasers to achieve the lowest attenua-Thus,ZnSe-based devices are stillof high interest because,in principle,they can coverHowever,successful production of bright,Òlong- (Received October 3,2001;accepted March 2,2002) tion intensity,with such a shift being considered ahallmark of a donor-acceptor pair (DAP) PL.PL of sample A shows a series of peaks at 2.686 eV,2.655 eV,2.625 eV,and 2.594 eV.These peaks areseparated by 30Ð31 meV,which is about the ZnSelongitudinal-optical phonon energy.However,it islear from Fig.1 that the intensity of the peak at2.686-eV peak,which indicates that these two peaksare associated,at least partly,with different centers.Also,we note that the peak at 2.655 eV is in the2.63Ð2.68-eV energy range,where we have previ-ously observed PL caused by excitons bound to Tepairs and/or clusters.Therefore,we suggest thatcombination of excitons bound to such Te complexes.As to the 2.686-eV peak,it is very close to the peakposition of the ÒdeepÓDAP emission in ZnSe:N.The current value is slightly high,but the presentsystem is expected to have a relatively strongsion,which could account for this.Furthermore,itcan be seen that,at low-excitation intensity,thiseV (Fig.3),which isin the range of the peak position(2.487 eV) of exc

2 itons bound to Telusters.Therefore,even
itons bound to Telusters.Therefore,even though the Te concentration is aslow as 0.5% in this sample,it still shows quite efÞ-cient Te-cluster-related PL.This can be understoodby considering the geometry of our sample,whichcould result in relatively high Te concentration in-doped layer.As to sample B,it shows only one broad peak ataround 2.457 eV.As mentioned,this peak shifts tored with decreasing excitation intensity.However,2.457 eV is too deep for the ÒordinaryÓDAP peaks inZnSe.Furthermore,as mentioned previously,thispeak is close to the one assigned to excitons bound tolusters.Therefore,we believe that,in additionto N,Te clusters are also involved in this transition.Previously,we reported PL spectra of another setGu,Kuskovsky,Neumark,Lin,Guo,Maksimov,and Tamargo Samples andSpacerN Doping(ML)(cm Uniform ZnSe:NN/A3.0 -ZnSe:(N)N/A5.6 -ZnSe:(Te,N)101.5 -ZnSe:(Te,N)124.0 -ZnSe:(Te,N)76.0 Fig. 1.The PLspectra of sample Aat different excitation intensities. Fig. 2.The PLspectra of sample B at different excitation intensities. Fig. 3.The PLspectra of sample Aat low-excitation intensity. higher Te concentrations (1.8% and 3%,respec-tively).It is instructive to compare those resultswith those of our new samples with less Te concen-trations (0.5%).In Fig.4,we plot the integrated in-tensity versus the excitation intensity for each ofour new samples,which show one slope for sample A-doped).Wenote t

3 hat with our previous samples,there are
hat with our previous samples,there are twodistinct slopes for each of them.Because the onlyprevious one is the Te concentration,the differencein slopes corroborates our conclusion that Te is in-volved in the PL.Regarding the two-slope case,asdiscussed in Refs.12 and 13,the plots show twoslopes if two recombination paths are present.We,thus,note that despite the low Te content of the newsample,the -layer region,enough togive two paths.We also note that the PL-peak posi-of the previous one.This could be due to the fact that-doped sample has more Teclus-ters,or alternatively,a sufÞciently high Te concen-tration to change the bandgap for this effect to takeplace.In summary,we employed a modulation-dopingtechnique that allowed us to achieve a net-acceptorwith Te lessthan 1.8%.The low-temperature PL spectra of thesesamples showed dominant Te-related peaks but alsoinvolved N.We also compared the PL spectra of ourpresent samples (with lower Te concentrations) tothat of previous samples (with higher Te concentra-tions).The results are consistent with our conclu-sion that Te clusters are involved in the PL.The authors acknowledge the support of the De-partment of Energy under Grant Nos.DE-FG02-1.R.Haitz,F.Kish,J.Tsao,and J.Nelson,Comp.Semicond.6,34 (2000).2.A.Weinert,Plastic Optical Fibers:Principles,Components,(Erlangen and Munich:Publicis MCD Verlag,3.G.F.Neumark,Mater.Lett.30,131 (1997).4.H.D.Jun

4 g,C.D.Song,S.Q.Wang,K.Arai,Y.H.Wu,Z.Zhu,
g,C.D.Song,S.Q.Wang,K.Arai,Y.H.Wu,Z.Zhu,and H.Katayama-Yoshida,Appl.Phys.Lett.5.W.Faschinger,J.Nurnberger,E.Kurtz,R.Schmitt,M.orn,K.Schull,and M.Ehinger,Semicond.Sci.Technol.12,1291 (1997).6.W.Lin,S.P.Guo,M.C.Tamargo,I.L.Kuskovsky,C.Tian,and G.F.Neumark,Appl.Phys.Lett.76,2205 (2000).7.I.L.Kuskovsky,Y.Gu,C.Tian,G.F.Neumark,S.P.Guo,W.Lin,O.Maksimov,M.C.Tamargo,A.N.Alyoshin,and V.M.Belous,Phys.Status Solidi (b)229,385 (2002).8.J.Lpankove,(New York:Dover,1974).9.H.Hartman,R.Mach,and B.Selle,ÒWide Gap IIÐVI Com-pounds as Electronic Materials,ÓCurrent Topics in Materi-vol.9,ed.E.Kaldis (Amsterdam:North-Hol-land,1982).10.I.L.Kuskovsky,C.Tian,G.F.Neumark,J.E.Spanier,I.P.Herman,W.Lin,S.P.Guo,and M.C.Tamargo,Phys.Rev.B63,155205 (2001).11.G.F.Neumark,L.Radomsky,and I.Kuskovsky,Proc.SPIE2346,159 (1994).12.I.L.Kuskovsky,C.Tian,C.Sudbrack,G.F.Neumark,W.-C.Lin,S.P.Guo,and M.C.Tamargo,Appl.Phys.90,2269.13.V.V.Serdyuk,G.G.Chemeresyuk,and M.Terek,trical Processes in Semiconductors(Kiev-Odessa:VischaShkola,1982) (in Russian).Heavily p-Type Doped ZnSe Using Te and N Co Doping 3Fig. 4.The integrated PLintensity as a function of laser-excitation-doped ZnSe:Te, N) and (b) -doped ZnSe:(Te, N). OnlineProo®ngGuidancePageFIRSTSTEP: InstallAdobeAcrobatReaderifyoudonotalreadyhavethisoranotherAcrobatproductinstalledonyourcomputer.YoucandothisfreeofchargebyconnectingtotheAdobesiteandfollowingtheinstructionsat:SECONDSTEP

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