Browsing by Author "CHANG, KM"

Now showing 1 - 10 of 10

2 NEW GENERALIZED EQUATIONS FOR MINORITY-CARRIER TRANSPORT IN BIPOLAR-TRANSISTORS WITH HEAVILY DOPED BASE AND NONUNIFORM BAND-STRUCTURE
(1992-06-01)
CHANG, KM
;
TSAI, JY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Two new, simple, general and rigorous closed-form integral solutions to the base current density and to the base transit time for electron transport in NPN bipolar transistors with heavily doped base and non-uniform band structure are presented. The expressions include the effects of non-uniform band structure, the influence of Fermi-Dirac statistics, the position-dependent mobility and the velocity saturation effect at the base-collector depletion-layer edge on the base side. An application of this new simplified base current density of equation to Early voltage in a narrow-base bipolar transistor is illustrated. A simple example for the effects of the minority-carrier density and of the base built-in field on the minority-carrier base transit time is also qualitatively discussed.
A CONSISTENT MODEL FOR CARRIER TRANSPORT IN HEAVILY DOPED SEMICONDUCTOR-DEVICES
(1988-08-01)
CHANG, KM
;
交大名義發表
;
電子工程學系及電子研究所
;
National Chiao Tung University
;
Department of Electronics Engineering and Institute of Electronics
A CONSISTENT MODEL FOR SEMICONDUCTOR HETEROJUNCTIONS IN EQUILIBRIUM
(1989-06-01)
CHANG, KM
;
電子工程學系及電子研究所
;
電控工程研究所
;
Department of Electronics Engineering and Institute of Electronics
;
Institute of Electrical and Control Engineering
A FIBEROPTIC REFLECTIVE DISPLACEMENT MICROMETER
(1995-06-01)
KO, WH
;
CHANG, KM
;
HWANG, GJ
;
交大名義發表
;
National Chiao Tung University
A simple fiber-optic reflection displacement micrometer with a sensitivity of 200 mV mu m(-1) and a resolution as low as 0.01 mu m is reported with a theoretical explanation of the experimental results. The sensor consists of a pulsed LED light source and a pair (A and B) of identical receiving fibers and photodetectors that detects the light reflected from the surface being measured. The differential signal (A-B) of the detectors is proportional to the displacement of the surface relative to a null position. The light intensity variation of the source and the reflectance change of the surface are compensated when the (A-B) signal is divided by the sum (A+B). The resolution is limited by noise and interference (vibration of the base). A resolution of 0.01 mu m can be achieved at narrow signal bands (d.c, to 3 Hz) excluding the low-frequency noise and vibration. The range, sensitivity and non-linearity can be adjusted according to the theory. The micrometer offers the advantages of non-contact, no electrical interference, simplicity, low cost and portability. It can be used in medical experiments and laboratory instruments.
A SIMPLE AND EFFICIENT PRETREATMENT TECHNOLOGY FOR SELECTIVE TUNGSTEN DEPOSITION IN LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION REACTOR
(1994-12-01)
CHANG, KM
;
YEH, TH
;
LI, CH
;
WANG, SW
;
電子工程學系及電子研究所
In this paper rye develop a two-step pretreatment method which is a simple but effective cleaning process that can be used to achieve a high deposition rate and excellent interface characteristics, as well as improve the selectivity. In the first step, we use CF4/O-2 mixing gases as a plasma etching system without substrate bias. The removal of damage and contaminants by reactive ion etching (RIE) during contact hole opening can thus be obtained. We consider that the role of oxygen is first to oxidize the polymer residues (i.e., fluorocarbons like CxFy) and the RIE-damaged regions on the silicon surface, and it is then followed with CF4 to remove these oxides. experiments, the plasma modification rate can be controlled at 120 Angstrom/min. Results of the high deposition rate, smooth interface, low selectivity loss and the other improvements are observed. These are superior to those of cases without pretreatment. The second step is that anhydrous HF cleaning was used to remove surface oxide which was formed during the first step. Obviously, this new cleaning technology is very efficient not only for contact hole pretreatment but also for polysilicon materials. This also implies that this technology may have potential for polycide gate applications.
ACTIVITY-COEFFICIENTS OF ELECTRONS AND HOLES IN DEGENERATE SEMICONDUCTORS WITH NONUNIFORM COMPOSITION
(1994-03-01)
CHANG, KM
;
YEH, TH
;
WANG, SW
;
LEE, CH
;
電子工程學系及電子研究所
A new simple, general and rigorous analytic expression for the equilibrium activity coefficients of electrons and holes in degenerate semiconductors with nonuniform composition is presented. These activity coefficients are functions of the carrier degeneracy (Fermi-Dirac statistics), the band gap, the electron affinity and the density of states which vary with position. The calculation of carrier activity coefficients requires the selection of chemical potential and electrostatic potential references. The choice of these reference states is addressed. The relationships between purely thermodynamic quantities and parameters of the band theory are also presented. Emphasis is also placed on formulating an equation in a simple, Boltzmann-like form in which the nonideal behavior is described by two parameters, the effective band-gap shrinkage, DELTAE(g), and the effective asymmetry factor, A. In this form the working equations for the carrier densities and activity coefficients are convenient for use in computer-aided analysis and design. The approach presented here allows convenient treatment of nonuniform degenerate semiconductors in a manner that is consistent with thermodynamics as well as with the Poisson-Boltzmann equation for the electrostatic potential.
ACTIVITY-COEFFICIENTS OF ELECTRONS AND HOLES IN SEMICONDUCTORS WITH NONUNIFORM COMPOSITION .1. NONDEGENERATE
(1988-11-01)
CHANG, KM
;
電子工程學系及電子研究所
;
電控工程研究所
;
Department of Electronics Engineering and Institute of Electronics
;
Institute of Electrical and Control Engineering
BAND DISCONTINUITIES - A SIMPLE ELECTROCHEMICAL APPROACH
(1990-04-01)
CHANG, KM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
NEW PHYSICAL FORMULATION OF THE THERMIONIC EMISSION CURRENT AT THE HETEROJUNCTION INTERFACE
(1993-07-01)
CHANG, KM
;
TSAI, JY
;
CHANG, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The thermionic emission current for electrons across the heterointerface is classically modeled as the difference between two opposing electron fluxes. Here we have developed a new consistent physical model, which includes the carrier degeneracy and nonideal behavior effects, for thermionic emission current at the heterojunction interface. It is shown that the thermionic emission current at the heterojunction interface can be expressed in a simple closed-form formalism which gives the relations among the average directional thermal velocity of electrons, the conduction band discontinuity, and the carrier activities at both sides of the interface. We also discuss the conditions under which the thermionic emission occurs at the heterointerface.
STRUCTURAL EFFECT ON BAND-TRAP-BAND TUNNELING INDUCED DRAIN LEAKAGE IN N-MOSFETS
(1995-12-01)
WANG, TH
;
CHANG, TE
;
HUANG, CM
;
YANG, JY
;
CHANG, KM
The structural dependence of the hot carrier stress incurred drain leakage current via band-trap-band tunneling in off-state has been modeled and characterized in conventional S/D, DDD, and LDD n-MOSFET structures, The results shows that lateral field enhanced band-trap-band tunneling is primarily responsible for an increased drain leakage current after hot carrier stress in LDD structures while vertical field induced tunneling is dominant in conventional S/D and DDD structures.