Electroreflectance And Photoreflectance Characterization Of The Space Charge Region In Semiconductors: Ito/Inp As A Model System

摘要: SummaryIn summary we have investigated the ER and PR spectra from SCR of model Schottky barrier systemITO /InP as a function reverse dc bias. For also varied amplitude ac modulatingvoltage. In addition to excitonic effects observed FKO which are functions Vbias but not Vac(for small modulation). this regime latter quantity affects envelope periodof FKO. The period these oscillations is direct measure surface electric field E doand modulating field. A generalized Franz -Keldysh theory, taking into consideration large built -inelectric fields, presented accounts for experimental results. From plot (E ac)2as obtained -in potential net carrier concentration device. Our work demonstrates electromodulation in barriers can be used an optical Mott -Schottky method that contactless determine fields.AcknowledgementsThe Brooklyn College group wishes acknowledge partial support IBM Shared University Re-search Program (SUR) New York State Foundation Science Technology part its Centerfor Advanced Program.84 / SP /E Vol. 794 Modern Optical Characterization Techniques Semiconductors Semiconductor Devices (1987)D-N Vbiag = 10.0 V D'-M' 1.0 again particular case position extrema changed because difference V^c. However, Fig. 4 larger ratio Proc*uces more rapid damping FKO.Displayed 6 at 300K ITO/InP sample using 6328A line He-Nelaser pump various values Vb^as.^^ Note increases spread out theyare less damped. Since beam constant ofvbias» t*ie bottom corresponds lowest value S. ac/ £ arbitrary phase factor, En energy ntn oscillation Eg gap. 4, 5 D (D1 ) n=l, feature (E1 has n=2, etc. he given by Eq. (2b) or (6b) . our appears *&Q j|c, field, so relevant.We performed systematic study variations both Vbias- Thus evaluate £1 |c applied bias voltage. Plotted 7 (£dc) Vbias' Both methods (ER PR) yield same result change with §c been evaluated Eqs. (7). We taken u \\ 0.073 mQ, where Q free electron mass. This y^ assumes due predominantly transitions heavy hole band conduction band. ^'^ light-hole should factor three smaller matrix ele­ ment effects.In fully depleted p-type related by:^5<£S)2 [4*e2(NA-V/Eo] (Vb. + V) (8) V, built-in potential.As seen (c.dc) ^s linear vbias» tnus allowing us Vj^ NA - (8). find Vbi -0.45±0.1 ND (1.55±0.1) x 10*6 cm"3, good agreement Hall effect measurements. measured experiment somewhat than those deduced prior studies on InP, Fermi level pinning states 1.2 eV 0.9 above valence band.^ Thus, preparation ITO treat­ samples served lower InP.Let now return exciton features A-C (A'-C1 ). sensitivity structures arises interference effect. there spatial variation dielectric oscillator strength photon energy. Over most absorption excitons negligible (which varies linearly distance surface) exceeds necessary ionize (of order several kV/cm). near "boundary11 between bulk, low enough become stable thus interact light. occurs light reflected interface region quenched. As width giving rise pattern energies below Eg. 0V 1.5V bias, 5.0V 9.0V 11.5V.In system Vac (for Jjc Franz-Keldysh (£§c^ V^. g Mott- Re­ search Center Program.