Pergamon NanaStrudurtd Materials. Vol. 8. No. 1. pp. 83-90.1997 Elsevia Science Ltd Copyi@ (b 1997 Acts Metallurgica Inc. Printed in the USA. All rights -cd 0965-9773197 $17.00 + .OO PII so9659773(97)08868-8 EFFECT OF LEVEL BROADENING ON THE PHOTOELECTRIC EMISSION FROM A SINGLE QUANTUM WELL IN ULTRATHIN FILM UNDER THE INFLUENCE OF A QUANTIZING MAGNETIC FIELD C. Bose, C. Chakraborty and C.K. Sarkar Department of Electronics and Tele-communication Engineering, Jadavpur University, Calcutta 700 032, INDIA zyxwvutsrqponmlkjihgfedcbaZY (Accepted November 1996) Abstract-The photoelectric emissionfromaquasi-two-dimensional electron gas (Q2DEG) in a single quantum well (SQW ) formed in wide-gap semiconductorfilms has been theoretically investigated, under magnetic quantization incorporating Landau level broadening arising due to electron impuriry scattering. The photoelectric current density has been computedfor a Q2DEG formed in n-type GaAs film and is found to be modified in the presence of level broadening. The photoemission zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA from a quasi-zero-dimensional electron gas (QODEG) formed in the ultrathin film under the influence of a quantizing zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA magnetic field applied normal to zyxwvutsrqponmlkjihgfedcbaZYXW the film has also been compared with thatfor the QODEG formed in a quantum box. INTRODUCTION Optoelectronics is rapidly emerging as the most promising branch of communication technology. The study of optoelectronic devices requires a good understanding of the optical processes like emission and absorption which occur in semiconductors. In this respect, photoelec- tric emission from a quasi-low-dimensional electron gas (QLDEG) formed in semiconductor nanostructures has been the subject of renewed interest (l-4). Application of a strong magnetic field leads to an additional carrier confinement in a two- dimensional semiconductor nanostructute and produces a set of discrete energy sub-bands known as Landau sub-bands. This permits the study of 1D or 2D carrier states analogous to carrier states in a quantum well wire or a quantum well box, respectively (5). To be more specific, a magnetic field normal to the surface of an ultrathin film causes total quantization of the carrier energy and the Q2DEG formed in the ultrathin film behaves as a quasi-zero dimensional gas in the presence of this quantizing magnetic field (8). Such a system, under ideal conditions, possesses a density of states (DOS) which is a set of delta-functions, their separation being dependent on the magnitude of the applied magnetic field. But even at very low temperatures, electron-impurity scattering will broaden the discrete energy levels and DOS takes on a Gaussian form. 83