Ion implantation damage of silicon as observed by optical reflection spectroscopy in the 1 to 6 eV region

Optical reflection spectra of crystalline, sputtered, and ion implanted silicon specimens are presented. Characteristic aspects of the spectra of ion implanted specimens are related to lattice damage

Complementary Symmetry Nanowire Logic Circuits: Experimental Demonstrations and in Silico Optimizations

Complementary symmetry (CS) Boolean logic utilizes both p- and n-type field-effect transistors (FETs) so that an input logic voltage signal will turn one or more p- or n-type FETs on, while turning an equal number of n- or p-type FETs off. The voltage powering the circuit is prevented from having a direct pathway to ground, making the circuit energy efficient. CS circuits are thus attractive for nanowire logic, although they are challenging to implement. CS logic requires a relatively large number of FETs per logic gate, the output logic levels must be fully restored to the input logic voltage level, and the logic gates must exhibit high gain and robust noise margins. We report on CS logic circuits constructed from arrays of 16 nm wide silicon nanowires. Gates up to a complexity of an XOR gate (6 p-FETs and 6 n-FETs) containing multiple nanowires per transistor exhibit signal restoration and can drive other logic gates, implying that large scale logic can be implemented using nanowires. In silico modeling of CS inverters, using experimentally derived look-up tables of individual FET properties, is utilized to provide feedback for optimizing the device fabrication process. Based upon this feedback, CS inverters with a gain approaching 50 and robust noise margins are demonstrated. Single nanowire-based logic gates are also demonstrated, but are found to exhibit significant device-to-device fluctuations

Optical Reflection Studies of Damage in Ion Implanted Silicon

Optical (3–6.5 eV) reflection spectra are presented for crystalline Si implanted at room temperature with 40 keV Sb ions to doses of less than 2×10^15/cm^2. These spectra, and their deviation from the reflection spectrum of crystalline Si, are discussed in terms of a model based on the average dielectric properties of the implanted region. For samples having a high ion dose (>10^15/cm^2) the observed spectra resemble the spectra of sputtered Si films. Anneal characteristics of the reflection spectra are found to be dose dependent. These observations are compared to, and found to substantiate, the results of other experimental techniques for studying lattice damage in Si

Direct interelectrode tunneling in GaSe

Using thin films of the layer compound gallium selenide, we have fabricated experimental structures which are nearly ideal for the study of tunneling currents. All of the parameters relevant to current flow in these structures can be independently determined since single-crystal gallium selenide films have the properties of the bulk material and also well-defined interfaces. A new analytical technique for determining the energy-momentum dispersion relation within the forbidden gap of a solid is discussed and applied to current-voltage data obtained from metal-GaSe-metal structures. The resulting E-k relation is shown to be an intrinsic property of GaSe. Tunneling currents in GaSe are shown to be quantitatively understood in terms of this E-k relation, the geometry of a given structure, and a simple model of current flow via tunneling

Contact-limited currents in metal-insulator-metal structures

The physical mechanisms underlying current flow in solid-state MIM structures are reviewed with emphasis on criteria for determining the dominant conduction mechanism in a given experimental situation. Measurements of the bias and temperature dependence of currents through structures incorporating a thin film of single-crystal gallium selenide are reported, and are shown to be in excellent agreement with the predictions of a simple physical model of contact-limited emission. Independently measured properties of bulk single-crystal gallium selenide are used in all calculations; no adjustable parameters are employed. We believe that this study presents unequivocal evidence for contact-limited thermionic currents in solid-state MIM structures

GaSe Schottky barrier gate FET

Advantages of the Schottky barrier gate technique are reviewed, and an experimental field-effect transistor constructed from p-type GaSe is discussed. Device characteristics are consistent with calculations based on material parameters and the geometry employed

Fundamental transition in the electronic nature of solids

Striking evidence for a fundamental covalent-ionic transition in the electronic nature of solids is presented

Tunneling Currents and the E-k Relation

The energy-momentum dispersion relation within the forbidden gap of a single-crystal insulator (in this case, GaSe) has been accurately determined using a simple physical model to describe tunneling currents in appropriate thin-film structures. This dispersion relation, calculated from experimental current-voltage data, is shown to be intrinsic to GaSe and capable of quantitatively predicting tunneling currents. The work reported here represents the first quantitative calculation of tunneling currents in metal-insulator-metal structures with all parameters relevant to the experiment independently determined