Drain Current DLTS Spectra and GaAs Substrate Crystal Effect on Low-Frequency-Oscillations of Si-Implanted MESFETs
- PDF / 391,420 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 12 Downloads / 161 Views
DRAIN CURRENT DLTS SPECTRA AND GaAs SUBSTRATE CRYSTAL EFFECT ON LOW-FREQUENCY-OSCILLATIONS OF Si-IMPLANTED MESFETs Yasuyuki SAITO, Tohru SUGA, Kazuhiko INOUE, Tatsuro MITANI, Yutaka TOMIZAWA, Johji NISHIO*, Kazutaka TERASHIMA**, Tohru KATSUMATA***, Katsuyoshi FUKUDA* Shoichi WASHIZUKA**c**, Satao YASHIRO****, Shigeoki TAKAMI****, Masahiro NAKAJIMA*-* and Masayuki WATANABE****. Micro-electronics CTR. Tamagawa Works. Toshiba Corp., 1,Komukai Toshiba-cho, Saiwai-ku, Kawasaki 210, Japan. *R&D CTR. Toshiba Corp. the same address. -*×(now) Toyo Univ. '(now) ERATO, JRDC. 2-13-1 Sengen,Tsukuba 305,Japan. Fac.Eng., 2100 Kujirai Nakanodai, Kawagoe 350, Japan. ****Semicond.Div., Toshiba Corp., 72 Horikawa-cho, Saiwai-ku, Kawasaki 210, Japan. ABSTRACT We report drain-current (Id) deep level transient spectroscopy (DLTS) (LEC) GaAs crystal spectra and liquid-encapsulated-Czochralski-technique effect on low-frequency-oscillation (LFO) of wide gate (400-jim) Si-implanted GaAs metal- semiconductor field- effect- transistors (MESFETs). In the range of this experiment we could not find distinguishing DLTS peaks surely to be linked with Id-LFO of the MESFETs. Stoichiometric-melt growth LEC-boules showed relatively large Id-LFO phenomena. As-rich-melt growth LEC-boules showed tolerance to Id-LFO. We conclude that Id-LFO is not directly linked to deep centers themselves but interaction between deep centers and potential profiles and electrons. Stability of potential profile or band or which affects Fermi-level profile depends on "pinning" center, quasi-Fermi-level stability. "Pinning" center such as EL2s of "LEC GaAs crystals" is essential. I NTRODUCTION Low-frequency-oscillation (LFO) phenomenon of drain current (Id) of Si-implanted GaAs metal- semiconductor- field- effect- transistors (MESFETs) reported.[1] It was described that heavily Cr-doped crystals do not show any Id-LFO. However, recently, wafers cut from undoped boules grown with liquidencapsulated- Czochralski- technique (LEC) are normally used. Strong Id-LFOs were sometimes observed on undoped LEC wafers.[2] Thus, we tracked down the Id-LFOs on undoped wafers by drain-current (Id) deep level transient spectroscopy (DLTS) [3,4,5] and various LEC undoped wafers with a wide-gate MESFETs as shown in Fig.l.[6,7,8] We report detailed DLTS spectra, and show Id-LFO dependence on crystal growth conditions. PART I: DRAIN CURRENT DLTS SPECTRA related phenomena. [1,9] Id-LFOs were discussed as deep center Therefore, we observed drain current DLTS spectra of the four MESFETs having large Id-LFOs and small Id-LFOs (as defined in Fig.2).[3,4,5] The Modefied Id-DLTS observation circuit[5] and the process condition are described in the previous reports.[5,7] The rate windows are 50/s and 20/s.
1 .3 Q4 02
cc LG
p, N SS.L
a. top view
-
2
Ti/Al ýtTAijuG e/Pt
4
-D 0.23
f ;L 0
1.5
tN
.--200 ICVDSiO V
4
S3 0 0~
GaAs -P
Vst-osc 10
_0
b.o-o'cross section~im) Fig.I(MESFET structure)
drin vo0tage(V) Fig.2(Id-LFO definition)
Mat. Res. Soc. Symp. Proc. Vol. 262. 01992 Materials Res
Data Loading...
