Primary Factor Extracted for Anomalous Decline of Drain Current in Metal–Oxide–Semiconductor Field-Effect Transistors

Abstract

A statistical approach has been exploratively applied to extract an influential factor of anomalous decreases in drain current observed in metal–oxide–semiconductor field-effect transistors with large channel widths. Since negative slopes were detected in drain current vs drain voltage (I d–V ds) curves even with negligible heat quantity or density, the self-heating effect was excluded as the primary factor. In contrast, the aspect ratio of the device areas showed a significant influence. These results support the validity of a hypothesis, namely, that acoustic standing waves are excited and thereby the probabilities of impact ionizations are synchronously magnified in the devices.

Sharp Resonance in a Metal–Oxide–Semiconductor Field-Effect Transistor with Multifinger Gate Configuration

“…The author attempted to generate an acoustic standing wave in the device using impact ionization incorporated with the stimulated emission of phonons. [4][5][6] Being fabricated using only a commercially available CMOS process, the new device preliminarily exhibited a sharp resonance at 300 MHz with a Q factor of over 1500, more than 100 times larger than that of LC resonators.…”

“…The structure and fabrication process of the above device are almost the same as those of the n-type MOS transistor described in detail elsewhere. 4,5) The device was fabricated using the CMOS process for 2.5 V transistors with a gate length (L) of 0.3 m and a total channel width W total of 400 m in the double-well structure on a p-type Si substrate with a thickness of 725 m (Fig. 1).…”

“…Taking the bias condition into account, it is reasonable to regard the current as being generated by impact ionization. 4,5) The negative R therefore suggests that the rate of creation of electron-hole pairs should be periodically changing at a fixed frequency corresponding to the high Q factor.…”

“…17) The other feasible mechanism may be impact ionization incorporated with stimulated phonon emission, as hypothetically introduced in a previous paper. 4) According to the impact ionization model, an acoustic wave is generated as a beat between slightly different frequencies of phonons. 6) The sharp resonance observed in this study is consistent with this hypothesis, because the excitation of coherent phonons is essential to generate a beat with high sharpness.…”

Steep Increase in Substrate Current in Metal–Oxide–Semiconductor Field-Effect Transistor with Multiple-Gate Configuration

“…13) The structure and fabrication of the MOSFET measured in this study are also described elsewhere. 8,13,14) The 2.5 V n-type MOSFET was fabricated in a double-well structure on a p-type Si substrate using a standard complementary metal-oxide-semiconductor (CMOS) process with the minimum gate length of L ¼ 0:3 m. Placed in a rectangular region surrounded by shallow-trench isolation (STI), multiple gate electrodes (N ¼ 40) with a width of W ¼ 40 m were connected in parallel to provide a total channel width of W total ¼ 1600 m. Four dummy gate electrodes (N dum ¼ 4) were inserted between all active gate electrodes to increase the interelectrode spacing (d ¼ 3:6 m), and connected in parallel to the ground potential in the following measurements. 8,13,14) I sub and I d were simultaneously measured for a device using a semiconductor parameter analyzer (Agilent 4156B) and a power unit (41501B), and plotted on a logarithmic scale as a function of V gs , as shown in Figs.…”