Negative photoconductivity and memory effects of germanium nanocrystals embedded in HfO2 dielectric.
A metal-insulator-semiconductor (MIS) structure containing an HfO2/SiO2 stack tunnel layer, isolated Germanium (Ge) nanocrystals, and an HfO2 capping layer, was obtained by an electron-beam evaporation method. A high-resolution transmission electron microscopy (HRTEM) study revealed that uniform and pronounced Ge nanocrystals had formed after annealing. Raman spectroscopy provided evidence for the formation of Ge-Ge bonds and the optimal annealing temperature for the crystallization ratio of the Ge. The electric properties of the MIS structure were characterized by capacitance-voltage (C-V) and current-voltage (I-V) measurements at room temperature. Negative photoconductivity was observed when the structure was under a forward bias, which screened the bias voltage, resulting in a decrease in the current at a given voltage and a negative shift in flat band voltage. A relatively high stored charge density of 3.27 x 10(12) cm 2 was also achieved.
The Research Center of Semiconductor Functional Film Engineering Technology, State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, PR China.
Shiye
S
Wang
Weili
W
Liu
Miao
M
Zhang
Zhitang
Z
Song
Chenglu
C
Lin
J Y
JY
Dai
P F
PF
Lee
H L W
HL
Chan
C L
CL
Choy
D004563:Electrochemistry; D005857:Germanium / Q000737:chemistry*; D006195:Hafnium / Q000737:chemistry*; D008854:Microscopy, Electron; D049329:Nanostructures / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D010777:Photochemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013059:Spectrum Analysis, Raman
D010087:Oxides; D005857:Germanium; D012822:Silicon Dioxide; D006195:Hafnium