Isolated isolectronic traps in semiconductors are promising candidates for single-photon emitters because sharp emission
lines with well-defined wavelengths are readily obtained. In this work, we study the emission from individual
isoelectronic traps formed by nitrogen-nitrogen pairs in nitrogen delta (δ)-doped GaAs grown on (001) and (111)A
substrates. We have found there is a remarkable difference in the polarization properties of luminescence for between
(001) and (111) substrates, and successfully obtained unpolarized single photons by utilizing (111) substrate, which are
desirable for the application to quantum cryptography. Unpolarized photons could also be obtained from nitrogen δ-
doped GaAs/AlGaAs heterostructures grown on (001) substrates.
193nm immersion and Hyper NA lithography are used at 45nm and beyond. The next generation of lithography will use a new technology such as Double Pattering, EUV or EB. Double patterning is one of the currently acceptable technologies.
Three common double pattern techniques are Litho-Etch-Litho-Etch (LELE), freezing, and sidewall (spacer) process. From a technical standpoint LELE is a very promising process, except for the second litho alignment. However, the cost of ownership will be very high because LELE will cost about twice as much as the current single litho patterning process. In order to build up a suitable double patterning technique, many device makers are developing unique processes. Two of these processes are freezing and sidewall. Flash memory makers are diligently investigating the sidewall process by CVD. This is because of the lack of a second litho alignment step, even with its high cost. The high cost of the CVD process can be reduced if a spin on material is used.
One of the goals of this paper is to reduce the cost of ownership by using spin on coatings for the sidewall process. Currently we are investigating this approach to control the sidewall width, profile and other properties.
In this research, the structural and electronic properties of a modulation-doped n-AlxGa1-xAs/GaAs heterostructure was nondestructively studied using spectroscopic ellipsometry (SE) and photoreflectance (PR). Se was used to characterize the thickness and Al composition x of the AlxGa1-xAs layer for the given sample. On the other hand, PR was used to determine the surface built-in electric field strength and the bandgap energy of the AlxGa1-xAs layer. The results of our analysis show that SE and PR, being complementary to each other, are useful methods in characterizing the given sample.
Photoellipsometry (PE), a contactless optical method, combines the features of both spectroscopic ellipsometry and photoreflectance (PR) and offers more complete information about the sample from a single experiment. PR, on the other hand, has been widely used for characterizing semiconductor microstructures. The nondestructive nature and the relatively sharper features produced in the measured spectra make this method very attractive. It was based on these advantages that we applied PE and PR to Si (delta) -doped GaAs. Two Si (delta) -doped GaAs samples were investigated in this study, each having an undoped GaAs cap layer of thickness (L equals 100 and 200 nm, respectively). Our main objective was to determine built-in electric field strength in the cap layer of each sample. In the analysis of the measured PE spectra, the Franz-Keldysh (FK) theory was used, taking into account the broadening and the photovoltage effects, whereas the measured PR spectra were analyzed using the asymptotic form of an Airy function for the FK oscillations. The results of our analysis show that, for each sample studied, the field strength obtained from PE spectra is in good agreement with that determined from PR spectra, and that the field strength decreases with the increase of the cap layer thickness.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.