Investigation of Nonequilibrium Many-Body Effects in        Semiconductors
{'Code': '07010000', 'Directorate': {'Abbreviation': 'ENG', 'LongName': 'Directorate For Engineering'}, 'Division': {'Abbreviation': 'ECCS', 'LongName': 'Div Of Electrical, Commun & Cyber Sys'}}
{'SignBlockName': 'Lawrence Goldberg', 'PO_EMAI': None, 'PO_PHON': None}
The optical properties of intrinsic semiconductors in the spectral              vicinity of their fundamental absorption edge are determined by the             interaction between photons and elementary excitations with the                 material.  One of the most important processes is the absorption of a           photon by means of simultaneous excitation of an electron from the              originally full valence band into the originally empty conduction               band.  Conduction-band electrons and valence-band holes are quantum-            mechanical quasi-particles.  The aim of this proposal is an                     experimental and theoretical study of nonequilibrium properties of a            high-density elecron-hole-pair system, which is generated resonantly            by femtosecond laser excitation.  The behavior of a high-density                nonthermal carrier distribution in semiconductors is very complex and           presently little is known.  The studies will use state-of-the-art               femtosecond laser and will focus on obtaining information on the                following topics:  (1) how effective is the screening attributable to           a nonequilibrium electron-hole distribution, and how does it differ             from the screening of a quasi-thermal equilibrium distribution; (2)             how does one describe the dynamics of screening associated with the             evolution from nonequilibrium to quasi-equilibrium carrier                      distributions; (3) what is the time scale for population                        thermalization, and when do the many-body Coulomb effects become                dominant; (4) under what conditions is it possible to observe optical           gain (non-equilibrium gain), and what are the relevant time scales to           obtain a population inversion.  Using laser pulses of approximately 10          fs, the dynamics of the semiconductors will be followed from the                initial nonequilibrium state to quasi-thermal equilibrium.  The                 semiconductors that will be investigated include CdS (or CdSe), GaAs,           and GaAs-A1GaAs multiple quantum wells.
[{'FirstName': 'Stephan', 'LastName': 'Koch', 'PI_MID_INIT': 'W', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'Stephan W Koch', 'EmailAddress': None, 'NSF_ID': '000438303', 'StartDate': '05/01/1989', 'EndDate': None, 'RoleCode': 'Co-Principal Investigator'}, {'FirstName': 'Nasser', 'LastName': 'Peyghambarian', 'PI_MID_INIT': None, 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'Nasser Peyghambarian', 'EmailAddress': 'nnp@u.arizona.edu', 'NSF_ID': '000218689', 'StartDate': '05/01/1989', 'EndDate': None, 'RoleCode': 'Principal Investigator'}]
{'Name': 'University of Arizona', 'CityName': 'TUCSON', 'ZipCode': '85721', 'PhoneNumber': '5206266000', 'StreetAddress': '845 N PARK AVE RM 538', 'StreetAddress2': None, 'CountryName': 'United States', 'StateName': 'Arizona', 'StateCode': 'AZ', 'CONGRESSDISTRICT': '07', 'CONGRESS_DISTRICT_ORG': 'AZ07', 'ORG_UEI_NUM': 'ED44Y3W6P7B9', 'ORG_LGL_BUS_NAME': 'UNIVERSITY OF ARIZONA', 'ORG_PRNT_UEI_NUM': None}
{'Name': None, 'CityName': None, 'StateCode': None, 'ZipCode': None, 'StreetAddress': None, 'CountryCode': None, 'CountryName': None, 'StateName': None, 'CountryFlag': None, 'CONGRESSDISTRICT': None, 'CONGRESS_DISTRICT_PERF': '""'}
{'Code': '151700', 'Text': 'EPMD-ElectrnPhoton&MagnDevices'}
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1988&All=true', 'xml': '8822305.xml'}