Accession Number : AD1011043

Title :   Capacitance-Voltage (CV) Measurement of Type-2 Superlattice Photodiodes

Descriptive Note : Technical Report,01 Dec 2011,29 Feb 2016

Corporate Author : Northwestern University Evanston Campus Evanston United States

Personal Author(s) : Chen,Andy ; Razeghi,Manijeh

Full Text :

Report Date : 05 Jan 2016

Pagination or Media Count : 32

Abstract : This is the final report presents work progress of this project from December 1st, 2011 to February 29th, 2016. This work is aimed to achieve a comprehensive understanding of the dynamics of impurities in the InAs/GaSb Type-II superlattice (T2SL). Capacitance-voltage measurement has been performed to calculate the ionized reduced impurity concentration of the material. Measurements performed in a wide temperature range (7 K to 300 K) allow the extraction of activation energies and total concentrations of impurities. The evolution of the total impurity concentration and their activation energies has been modeled theoretically and compared with experimental findings.Ionized carrier concentration versus temperature dependence revealed the presence of a kind of defects with activation energy below 6meV and a total concentration of low 1015 cm-3. Correlation between defect characteristics and superlattice designs were studied. The defects exhibited a p-type behavior with decreasing activation energy as the InAs thickness increases from 7 to 11 monolayers, while maintaining the GaSb thickness of 7 monolayers. With 13 monolayers of InAs, the superlattice becomes n-type and the activation energy deviates from the p-type trend.Capacitance-voltage technique was also utilized to characterize the carrier concentration of gallium-free InAs/InAs1-xSbx type-II superlattice p-i-n photodiodes as a function of growth temperature and Beryllium (Be) compensated doping. The unintentionally doped InAs/InAs0.45Sb0.55 superlattice photodiode grown at 395oC with 100% cut-off wavelength at 12 micro m has residually n-type carrier concentration of 1.610(expn 15) cm( expn -3) at 77K. The background carrier concentration can be reduced by optimizing growth temperature and by Be-compensation doping. Different kinds of defects exist in the undoped InAs/InAs1-xSbx type-II superlattice and their dependence on the growth temperature was also investigated.

Descriptors :   Superlattices , capacitance , voltage , measurement , defects , Photodiodes , Impurities , semiconductors , Activation energy , temperature , layers , Long wavelengths , Infrared radiation , gallium , Indium arsenides , Gallium antimonides

Distribution Statement : APPROVED FOR PUBLIC RELEASE