Optical Determination of Mean Free Path of Hot Electrons in Metals

Abstract

Light emission via surface plasmon excitation can be used as a sensitive detector for hot electrons in metal-insulator-metal structures. Ballistic and electron-electron scattering mean free path values obtained for silver with this method in the 2.19 to 2.44 eV energy range are in good agreement with theoretical predictions. CBeT, IIOJlJWeHHbIfi npH PaCIIaEe IIOBePXHOCTHbIX HJIa3MOHOB MOXWT CJIYXWlTb 9YBCTBH-TenbHbIM AeTeKTOpOM rOPR9EIX BJIBIETPOHOB B TOHKOILTeH09HbIX CTPYKTYPaX TMna Me-Tanz-oKmen-MeTann. IIonyqeHHare c noMombm 3~01-0 MeTona B TOHKUX nnemax ce-pe6pa ~~J I~U C T H~~C K U~ cpenme ~J I E I H H CBO60~HOrO npo6era BJI~KTPOHOB EI cpemnie I[nUHbI CBO60~HOrO npo6era 3neKTpOH-3neKTpOHHOrO paCCeRHHR HaXOAFITCR B XOpOIueM COrJIaCEIA C TeOpeTEIgeCKUMH OUeHKaMEI B EIHTepBane 3HePrHII 2,19 A0 2,44 e v . l ) Konkoly Thege ut. 29-33, Budapest XII, Hungary. 15'

On the mechanism of photon emission from thin film tunnel structures

“…The presenee of roughness with eorrelations of this order was diseovered not only in the present work but also in [19] and [20]. Ir was proved by us and deseribed in [8] that for smooth substrates this is the dominant eomponent of emission.…”

“…only statistieally eorrugated surfaces. Since, however, our experiments on AI--AI~O 3 --Ag diodes made on smooth substrate seemed to contradict to these results [8] it was decided to perform a detailed study of MOM structures with noble metal anode fflms.…”

“…At the same time results of [8] the emitted light originates from the vacuum-metal interface, i.e. the mechanism described under (ii) is not effective in the emission of unpolarized light in the hv < E a energy range.…”

“…Since there is no other known direct method to measure 2 s in the 1.5 eu < < E ~ 4 eV region of electron energy, the described technique, reviewed in detail in [8], seems to be a useful tool to study electron propagation in the given energy region. At the same time results of [8] the emitted light originates from the vacuum-metal interface, i.e.…”

“…If the electrons are not monochromatic as deduced from Fig. 3, p(r E) can be calculated as given in [8] andas a result hv > E c SPO and therefore photons can also be observed. This process can clearly also be seen for Ag where the shape of the speetrum at around E c ~ E d = 3.87 eV is determined essentially by (4) as seen in Fig.…”