Epitaxy-based device

Table 9.1 shows the quahtative classification of the above-mentioned data. The advantage of LEG over VGF SI GaAs is the higher mesoscopic homogeneity of the electrical properties. This is particularly suitable for microelectronic devices produced in a wafer by ion implantation (MESFETs). On the other hand, VGF GaAs wafers with a lower epd are preferred for epitaxy-based devices like HEMTs and HBTs. 

The main advantages that compound semiconductor electronic devices hold over their siUcon counterparts He in the properties of electron transport, excellent heterojunction capabiUties, and semi-insulating substrates, which can help minimise parasitic capacitances that can negatively impact device performance. The abiUty to integrate materials with different band gaps and electronic properties by epitaxy has made it possible to develop advanced devices in compound semiconductors. The hole transport in compound semiconductors is poorer and more similar to siUcon. Eor this reason the majority of products and research has been in n-ty e or electron-based devices. 

Rare earth element doped alkaline earth sulfides are employed in luminescence-based devices like thin film electroluminescent displays [119,120] and devices for optical data storage [121]. Strontium sulfide, SrS, thin films have been prepared by atomic layer epitaxy from [Sr(tmhd)2] (tmhd" 7) in the presence of HiS [122]. Additionally, solid sources have been employed in a comparable CVD approach [122b]. 

While considerable progress was made in thin-fihn growth of nonpolar GaN from 2000-2002, thick-film or bulk growth of nonpolar orientations continued to be elusive until late 2002. The performance of nonpolar GaN-based devices would be limited by the lack of low-defect density film and substrate options. This chapter describes the progress achieved in thick-film nonpolar GaN growth via hydride vapor phase epitaxy (HVPE) toward the goal of producing low-defect density nonpolar GaN thick-films and substrates. 

Since optoelectronic properties of GaN-based devices strongly depend on the structural quality of the heterostructure layers, the first part of this chapter will discuss the defects formed in GaN -plane layers grown on nonpolar (1120) 4H-SiC. In the second part of this chapter, pendeo-epitaxial and laterally overgrown epitaxial layers will be characterized and possible defect reduction using these methods will be discussed. Transmission electron microscopy (TEM) methods will be used to characterize these defects. 

GaAs, GaAlAs, and GaP based laser diodes are manufactured using the LPE, MOCVD, and molecular beam epitaxy (MBE) technologies (51). The short wavelength devices are used for compact disc (CD) players, whereas the long wavelength devices, mostly processed by MBE, are used in the communication field and in quantum well stmctures. 

Arsenic from the decomposition of high purity arsine gas may be used to produce epitaxial layers of III—V compounds, such as Tn As, GaAs, AlAs, etc, and as an n-ty e dopant in the production of germanium and silicon semiconductor devices. A group of low melting glasses based on the use of high purity arsenic (24—27) were developed for semiconductor and infrared appHcations. 

Cathodoluminescence microscopy and spectroscopy techniques are powerful tools for analyzing the spatial uniformity of stresses in mismatched heterostructures, such as GaAs/Si and GaAs/InP. The stresses in such systems are due to the difference in thermal expansion coefficients between the epitaxial layer and the substrate. The presence of stress in the epitaxial layer leads to the modification of the band structure, and thus affects its electronic properties it also can cause the migration of dislocations, which may lead to the degradation of optoelectronic devices based on such mismatched heterostructures. This application employs low-temperature (preferably liquid-helium) CL microscopy and spectroscopy in conjunction with the known behavior of the optical transitions in the presence of stress to analyze the spatial uniformity of stress in GaAs epitaxial layers. This analysis can reveal,... 

The proposed technique seems to be rather promising for the formation of electronic devices of extremely small sizes. In fact, its resolution is about 0.5-0.8 nm, which is comparable to that of molecular beam epitaxy. However, molecular beam epitaxy is a complicated and expensive technique. All the processes are carried out at 10 vacuum and repair extrapure materials. In the proposed technique, the layers are synthesized at normal conditions and, therefore, it is much less expansive. The presented results had demonstrated the possibility of the formation of superlattices with this technique. The next step will be the fabrication of devices based on these superlattices. To begin with, two types of devices wiU be focused on. The first will be a resonant tunneling diode. In this case the quantum weU will be surrounded by two quantum barriers. In the case of symmetrical structure, the resonant... 

Gold has been used for many years as a minority carrier lifeline controller in Si. As such, it is introduced in a controlled manner, usually by diffusion into transistor structures to decrease the carrier lifetime in the base region in order to increase the switching speed (Ravi, 1981). Conversely, the uncontrolled presence of Au is clearly deleterious to the performance of devices, both because of the increased recombination within the structure and the increase of pipe defects, which can cause shorting of the device. These pipe defects consist of clusters of metallic impurities at dislocations bounding epitaxial stacking faults. 

Silicon-based pressure sensors are amongst the most common devices making use of this process. A thin low-n-doped epitaxial layer on the wafer determines an etch stop depth and thus the thickness of e.g. the pressure sensor membrane. 

---