Low temperature magneto-photoluminescence characterization of high purity gallium arsenide and indium phosphide

Low-temperature magneto-photoluminescence is a very powerful technique to characterize high purity GaAs and InP grown by various epitaxial techniques. These III-V compound semiconductor materials are used in a wide variety of electronic, optoelectronic and microwave devices. The large binding energy differences of acceptors in GaAs and InP make possible the identification of those impurities by low-temperature photoluminescence without the use of any magnetic field. However, the sensitivity and resolution provided by this technique rema1ns inadequate to resolve the minute binding energy differences of donors in GaAs and InP. To achieve higher sensitivity and resolution needed for the identification of donors, a magneto-photoluminescence system 1s installed along with a tunable dye laser, which provides resonant excitation. Donors 1n high purity GaAs are identified from the magnetic splittings of "two-electron" satellites of donor bound exciton transitions 1n a high magnetic field and at liquid helium temperature. This technique 1s successfully used to identify donors 1n n-type GaAs as well as 1n p-type GaAs in which donors cannot be identified by any other technique. The technique is also employed to identify donors in high purity InP. The amphoteric incorporation of Si and Ge impurities as donors and acceptors in (100), (311)A and (3ll)B GaAs grown by molecular beam epitaxy is studied spectroscopically. The hydrogen passivation of C acceptors in high purity GaAs grown by molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) 1s investigated using photoluminescence. Si acceptors ~n MBE GaAs are also found to be passivated by hydrogenation. The instabilities in the passivation of acceptor impurities are observed for the exposure of those samples to light. Very high purity MOCVD InP samples with extremely high mobility are characterized by both electrical and optical techniques. It is determined that C is not typically incorporated as a residual acceptor ~n high purity MOCVD InP. Finally, GaAs on Si, single quantum well, and multiple quantum well heterostructures, which are fabricated from III-V semiconductors, are also measured by low-temperature photoluminescence.

Knowledge management capabilities and organizational performance: an investigation into the effects of knowledge infrastructure and processes on organizational performance

Knowledge is one of the most important assets for surviving in the modern business environment. The effective management of that asset mandates continuous adaptation by organizations, and requires employees to strive to improve the company's work processes. Organizations attempt to coordinate their unique knowledge with traditional means as well as in new and distinct ways, and to transform them into innovative resources better than those of their competitors. As a result, how to manage the knowledge asset has become a critical issue for modern organizations, and knowledge management is considered the most feasible solution. Knowledge management is a multidimensional process that identifies, acquires, develops, distributes, utilizes, and stores knowledge. However, many related studies focus only on fragmented or limited knowledge-management perspectives. In order to make knowledge management more effective, it is important to identify the qualitative and quantitative issues that are the foundation of the challenge of effective knowledge management in organizations. The main purpose of this study was to integrate the fragmented knowledge management perspectives into the holistic framework, which includes knowledge infrastructure capability (technology, structure, and culture) and knowledge process capability (acquisition, conversion, application, and protection), based on Gold's (2001) study. Additionally, because the effect of incentives ̶̶ which is widely acknowledged as a prime motivator in facilitating the knowledge management process ̶̶ was missing in the original framework, this study included the importance of incentives in the knowledge management framework. This study also identified the relationship of organizational performance from the standpoint of the Balanced Scorecard, which includes the customer-related, internal business process, learning & growth, and perceptual financial aspects of organizational performance in the Korean business context. Moreover, this study identified the relationship with the objective financial performance by calculating the Tobin's q ratio. Lastly, this study compared the group differences between larger and smaller organizations, and manufacturing and nonmanufacturing firms in the study of knowledge management. Since this study was conducted in Korea, the original instrument was translated into Korean through the back translation technique. A confirmatory factor analysis (CFA) was used to examine the validity and reliability of the instrument. To identify the relationship between knowledge management capabilities and organizational performance, structural equation modeling (SEM) and multiple regression analysis were conducted. A Student's t test was conducted to examine the mean differences. The results of this study indicated that there is a positive relationship between effective knowledge management and organizational performance. However, no empirical evidence was found to suggest that knowledge management capabilities are linked to the objective financial performance, which remains a topic for future review. Additionally, findings showed that knowledge management is affected by organization's size, but not by type of organization. The results of this study are valuable in establishing a valid and reliable survey instrument, as well as in providing strong evidence that knowledge management capabilities are essential to improving organizational performance currently and making important recommendations for future research.