Browsing by Author "Jung, TG"

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Disordered Si/SiGe superlattices grown by ultrahigh vacuum chemical vapor deposition
(1996-02-01)
Chang, TC
;
Yeh, WK
;
Chang, CY
;
Jung, TG
;
Tsai, WC
A series of Si/Si1-xGex disordered superlattices with various degrees of disorder were grown in an ultrahigh vacuum chemical vapor deposition system (UHV/CVD). High-resolution double-crystal X-ray diffraction (HRXRD), and conventional cross-sectional transmission electron microscopy were used to evaluate the crystalline quality of these superlattices. A dynamical X-ray simulation program was employed to analyze the experimental rocking curves, Excellent matches between experimental rocking curves and simulated ones were obtained for all superlattices with various degrees of disorder.
Interfacial abruptness in Si/SiGe heteroepitaxy grown by ultrahigh vacuum chemical vapor deposition
(1997-09-01)
Tsai, WC
;
Chang, CY
;
Jung, TG
;
Chang, TC
;
Lin, HC
High-quality Si/Si1-xGex strained-layer superlattices have been grown in the temperature range 525 degrees C-550 degrees C by ultrahigh vacuum chemical vapor deposition. We employed X-ray reflection and high-resolution double-crystal X-ray diffraction measurements to study the dimensional and compositional variations in a Si/Si1-xGex superlattice. From the X-ray reflection results, the interfacial roughness of Si layers on SiGe, and SiGe layers on Si, is 0.1nm for growth at 525 degrees C and 0.2nm for growth at 550 degrees C. A simple model for estimating the interfacial abruptness of Si/Si1-xGex heterojunctions is proposed. In this model, a transition region with a linearly graded Ge composition is assumed to exist at both Si/Si1-xGex interfaces. The Ge composition x of a Si/Si1-xGex superlattice is found to increase with the growth time at a constant gas phase composition. This phenomenon can be explained by this model, and the thickness of the transition region and the transition time can be extracted from these fitting results. The transition thicknesses are found to be about 0.3-0.7nm for growth at 525 degrees C and 1-1.5nm for growth at 550 degrees C.
Interfacial abruptness in Si/SiGe heteroepitaxy grown by ultrahigh vacuum chemical vapor deposition
(1997-09-01)
Tsai, WC
;
Chang, CY
;
Jung, TG
;
Chang, TC
;
Lin, HC
High-quality Si/Si1-xGex strained-layer superlattices have been grown in the temperature range 525 degrees C-550 degrees C by ultrahigh vacuum chemical vapor deposition. We employed X-ray reflection and high-resolution double-crystal X-ray diffraction measurements to study the dimensional and compositional variations in a Si/Si1-xGex superlattice. From the X-ray reflection results, the interfacial roughness of Si layers on SiGe, and SiGe layers on Si, is 0.1nm for growth at 525 degrees C and 0.2nm for growth at 550 degrees C. A simple model for estimating the interfacial abruptness of Si/Si1-xGex heterojunctions is proposed. In this model, a transition region with a linearly graded Ge composition is assumed to exist at both Si/Si1-xGex interfaces. The Ge composition x of a Si/Si1-xGex superlattice is found to increase with the growth time at a constant gas phase composition. This phenomenon can be explained by this model, and the thickness of the transition region and the transition time can be extracted from these fitting results. The transition thicknesses are found to be about 0.3-0.7nm for growth at 525 degrees C and 1-1.5nm for growth at 550 degrees C.
Light emission from the porous boron delta-doped Si superlattice
(1996-02-01)
Chang, TC
;
Yeh, WK
;
Hsu, MY
;
Chang, CY
;
Lee, CP
We report the first study on the porous boron delta-doped Si superlattice. Visible photoluminescence (PL) was observed with multiple peaks from the porous boron delta-doped Si superlattice at room temperature. In the electroluminescence (EL) experiment, a bright yellow light emission was observed from the porous boron delta-doped Si superlattices. However, a weak red light emission was also observed from the conventional porous Si which is anodized at the same etching condition. As a result, the structure of the porous boron delta-doped Si superlattice has the ability of controlling the quantum size in porous Si and enhancing the light intensity from porous Si.
Uniformity of epilayer grown by ultrahigh-vacuum chemical vapor deposition
(1996-04-01)
Chang, TC
;
Yeh, WK
;
Chang, CY
;
Jung, TG
;
Tsai, WC
In this work, we explored the Ge fraction, layer thickness and dopant concentration uniformity of epilayers grown by an ultrahigh-vacuum chemical vapor deposition system (UHV/CVD). Three epilayers were grown for this study: a single epilayer of SiGe, a heavily boron doped Si epilayer and a Si/SiGe superlattice with p(+) Si cap. The uniformity in a wafer was measured to be less than +/- 1.5%. In addition, we explored the wafer-to-wafer uniformity of a strained SiGe layer. The variations in thickness and composition between two samples grown in the same run were evaluated to be +/- 1.3 and +/- 1.2%, respectively. These results show that uniform layers can be simultaneously obtained on many wafers by the UHV/CVD system.