@phdthesis{Trushin2011, author = {Trushin, Maxim}, title = {Electronic properties of interfaces produced by silicon wafer hydrophilic bonding}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-22841}, school = {BTU Cottbus - Senftenberg}, year = {2011}, abstract = {The thesis presents the results of the investigations of electronic properties and defect states of dislocation networks (DNs) in silicon produced by wafers direct bonding technique. Practical interest for the investigations in this area issued - first of all - from the potential application of such dislocation networks in microelectronics as all-Si light emitter for on-chip interconnection. Besides, dislocation networks may serve as a perfect model object to get new information about the fundamental properties of dislocations and grain boundaries in Si, what is of particular importance for multicrystalline silicon solar cells performance. Despite of a long story of studying of dislocations in silicon, a new insight into the understanding of their very attractive properties was succeeded due to the usage of a new, recently developed silicon wafer direct bonding technique, allowing to create regular dislocation networks with predefined dislocation types and densities. Samples for the investigations were prepared by hydrophilic bonding of p-type Si (100) wafers with same small misorientation tilt angle (~0,5°), but with four different twist misorientation angles Atw (being of <1°, 3°, 6° and 30°, respectively), thus giving rise to the different DN microstructure on every particular sample. The main experimental approach of this work was the measurements of current and capacitance of Schottky diodes prepared on the samples which contained the dislocation network at a depth that allowed one to realize all capabilities of different methods of space charge region spectroscopy (such as CV/IV, DLTS, ITS, etc.). The key tasks for the investigations were specified as the exploration of the DN-related gap states, their variations with gradually increasing twist angle Atw, investigation of the electrical field impact on the carrier emission from the dislocation-related states, as well as the establishing of the correlation between the electrical (DLTS), optical (photoluminescence PL) and structural (TEM) properties of DNs. The most important conclusions drawn from the experimental investigations and theoretical calculations can be formulated as follows: - DLTS measurements have revealed a great difference in the electronic structure of small-angle (SA) and large-angle (LA) bonded interfaces: dominating shallow level and a set of 6-7 deep levels were found in SA-samples with Atw of 1° and 3°, whereas the prevalent deep levels - in LA-samples with Atw of 6° and 30°. The critical twist misorientation angle separating SA- and LA- interfaces was estimated as Atw*≈ 3,5±0,5°, what agrees quiet well with the results of previous PL and TEM investigations. - For the dominating shallow traps in SA-samples (denoted as ST1/ST3 traps) a new phenomenon - that is 'giant Poole-Frenkel effect' of enhanced carrier emission due to dislocations elastic strain field was observed for the first time. Performed theoretical calculations have shown that in the investigated samples such an effect should be ascribed to the row of 60° dislocations rather than to the mesh of screw ones. In this respect, shallow traps ST1/ST3 were identified either with shallow 1D bands (directly or as being coupled with them) or with shallow stacking fault states on splitted 60° dislocation. - From the comparison and correlations of measured DLTS spectra with the results of PL and TEM investigations it was established, that shallow ST1/ST3 traps participate in D1 radiative recombination and that the structural elements, responsible for D1 luminescence of small-angle DNs, are the triple knots (intersections with screw dislocations) along the 60° dislocations. However, the optimal density of 60° dislocations as well as of triple knots, in other words - the optimal tilt and twist misorientation angles for maximal D1 intensity - needs further clarification.}, subject = {Elektronische Eigenschaft; Siliciumbauelement; Bonden; Wafer; Silicium; Versetzungsnetzwerk; Poole-Frenkel Effekt; DLTS; D1 Lumineszenz Band; Dislocation networks; DLTS; Poole-Frenkel effect; D1 Luminescence band}, language = {en} } @phdthesis{Dombrowski2000, author = {Dombrowski, Kai F.}, title = {Micro-raman investigation of mechanical stress in Si device structures and phonons in SiGe}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-000000031}, school = {BTU Cottbus - Senftenberg}, year = {2000}, abstract = {This thesis consists of two parts. The first part presents an investigation of mechanical stress in silicon device structures processed with variations of the shallow trench isolation (STI) process. The measurements were performed with high spatial resolution using micro-Raman spectroscopy with ultra-violet (364 nm) laser light to excite the Raman scattering. This thesis describes in detail the advantages of UV over visible light excitation. The influence of different process parameters on the amount of mechanical stress introduced into the silicon substrate is presented. A correlation of mechanical stress levels with defect generation and degrading electrical properties is shown. The second part of this thesis presents an investigation of phonons in SiGe bulk crystals. These measurements were performed using Raman spectroscopy to clarify the assignments of various vibrational modes and explain the shift of the Ge phonon as small amounts of Si are added into a pure Ge crystal. In addition, the silicon local vibrational modes (LVM) of all three silicon isotopes are shown, thus verifying the assignment of this mode experimentally.}, subject = {Siliciumbauelement; Elastische Spannung; Raman-Spektroskopie; Silicium; Germanium; Mischkristall; Phonon; Raman-Spektroskopie; Mechanical stress; Raman; UV; Shallow trench isolation; Local vibrational mode}, language = {de} } @phdthesis{Vasylyev2006, author = {Vasylyev, Andriy}, title = {Integrated RF power amplifier design in Silicon-based technologies}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-202}, school = {BTU Cottbus - Senftenberg}, year = {2006}, abstract = {This thesis presents the design and implementation of the RF power amplifiers in modern silicon based technologies. The main challenge is to include power amplifier on a single chip with output power level in watts, operating at high frequencies where the transit frequency (fT) is just a few times higher than the operating frequency. This work describes the design procedure for bipolar and CMOS transformer-based Class-A, Class-AB and Class-B power amplifiers. The design procedure is based on the HICUM for bipolar and BSIM4 for CMOS transistor models and is divided in four parts: •Building a one transistor prototype power amplifier which is based on the analytical analysis of the output characteristics and transistor model. •Load-pull simulation to define the final input and output impedances. •Derivation of the analytical equations for the transformer-based matching network. •Design of the final transformer-based push-pull power amplifier. A good agreement between the proposed analytical analysis and large-signal (harmonic balance) simulation results proofs usefulness of the proposed power amplifier design approach. Additionally, it shows the contribution of the separated devices at the final design that helps to find a technology limits in the current circuit design. The main achievements include: •A 2.4 GHz power amplifier in 0.13 um CMOS technology. An output power of 28 dBm is achieved with a power added efficiency of 48 \% at a supply voltage of 1.2 V [Vasylyev 04]. •Two 17 GHz power amplifiers in 0.13 um CMOS technology (one fully integrated while the other with external matching network) with output power exceeding 50 mW. The former exhibits a power added efficiency of 9.3 \% while the latter a 15.6 \% power added efficiency [Vasylyev 06]. •A fully integrated K and Ka bands power amplifier in 0.13 um CMOS technology. A 13 dBm output power along with power added efficiency of 13 \% is achieved at an operating frequency of 25.7 GHz with 1.2 V supply [Vasylyev 05,a]. •A fully integrated power amplifier based on a novel power combining transformer structure in 28 GHz-fT SiGe-bipolar technology. A 32 dBm output power along with power added efficiency of 30 \% is achieved at an operating frequency of 2.12 GHz with 3.5 V supply [Vasylyev 05,b].}, subject = {Siliciumbauelement; Radiofrequenzbereich; Verst{\"a}rker; Leistungsverst{\"a}rker; CMOS; Power amplifier; CMOS}, language = {en} }